JP4188047B2 - Leukocyte-containing liquid filtration method and apparatus - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、白血球含有液から凝集物や白血球等の好ましくない成分を除去する為の白血球除去フィルターを用いて白血球含有液を濾過する方法、及びそのための装置に関する。特に、可撓性容器からなる白血球除去フィルターを使用してポンプなどを使用して高流速で白血球含有液を濾過する場合に、白血球除去フィルターの膨らみを防止して白血球除去フィルターの厚みを適切に保持して流れを均一にするための体積拘束板を使用した濾過に関する。
【０００２】
【従来の技術】
輸血の分野においては、血液製剤中に含まれている混入白血球を除去してから血液製剤を輸血する、いわゆる白血球除去輸血が普及してきている。これは、輸血に伴う頭痛、吐き気、悪寒、非溶血性発熱反応などの比較的軽微な副作用や、受血者に深刻な影響を及ぼすアロ抗原感作、ウィルス感染、輸血後GVHDなどの重篤な副作用が、主として輸血に用いられた血液製剤中に混入している白血球が原因で引き起こされることが明らかにされたためである。
【０００３】
白血球除去方法には、大きく分けて遠心分離機を用いて血液成分の比重差を利用して白血球を分離除去する遠心分離法と、繊維素材や、連続気孔を有する多孔質体などの多孔質素子からなるフィルター材を用いて白血球を除去するフィルター法の２種類がある。フィルター法は、白血球除去能に優れていること、操作が簡便であること、及びコストが安いことなどの利点を有するため現在普及している。
【０００４】
フィルター法、即ち、白血球除去フィルターによる血液製剤などの白血球含有液の処理は、輸血操作を行う際にベッドサイドで行われることが多かったが、近年では白血球除去血液製剤の品質管理、及び白血球除去処理の有効性向上の為に、血液センターにおいて保存前に行われることが一般的になりつつある。
【０００５】
従来白血球除去フィルターには、不織布や多孔質体からなるフィルター要素をポリカーボネート等の硬質容器に充填したものが広く使われてきたが、
１）容器が水蒸気透過性を有さないため、採血分離セットの滅菌工程として広く使われている高圧蒸気滅菌を適用し難い。
２）採血分離セットに白血球除去フィルターを組み込んだ、いわゆるクローズドシステムを使用し、全血を遠心分離によって複数の血液成分に分離した後に白血球除去を行う場合には、白血球除去フィルターも採血分離セットと共に遠心されるため、この際、硬質の容器がバッグや導管にダメージを与えたり、硬質容器自身が遠心時のストレスに耐えられずに破損する可能性がある。
などの問題点を有するために、これらの問題点を解消する方法として、可撓性素材を容器に用いた、可撓性の白血球除去フィルターが開発されている。
【０００６】
通常これらの白血球除去フィルターで血液を濾過する際は、濾過されるべき血液製剤が入ったバッグを、フィルターよりも100cm程高い位置に置き、重力の作用によって血液製剤を濾過するのが一般的である。
しかし近年、市場においては白血球除去フィルターに対する要求として、短時間で所望量の血液を処理し作業時間を短縮化させたいといった要求がある。
【０００７】
一方、近年、先進国において少子高齢化が進行しており、献血可能人口が減少しつつある。献血可能人口の減少に伴い献血者が減少し、輸血に必要な血液の不足が近い将来、深刻な問題となることが懸念されている。このような問題を回避するために、一人の献血者から多量の血液を採取し、輸血に必要な血液を確保することが検討されている。この場合、一回に多量の血液、具体的には従来の１．５倍から２倍の血液を濾過することになり、さらには、短時間で多量の血液を濾過し作業時間を短縮化させたいといった要求もある。
このため、従来広く行われてきた重力の作用によって血液製剤を濾過する方法の他に、ポンプなどで濾過する血液を加圧し、白血球除去フィルターに流し込むことで血液の濾過速度を大きくして、短時間で血液を濾過する方法が検討されている。
【０００８】
従来技術において、短時間で多量の血液を濾過し作業時間を短縮化する技術手段として、白血球除去フィルターの濾過部断面積を大きくすることが考えられる。白血球除去フィルターが組み込まれた採血分離セットを遠心しない用途に対しては、濾過部断面積を拡大した硬質素材容器の白血球除去フィルターの利用が考えられる（特許文献１参照）。しかし、濾過部断面積の拡大された硬質素材容器の白血球除去フィルターでは、容器全周にわたって均一に溶着することが困難であり、部分的に溶着強度が弱い部位が形成されてしまう。このような白血球除去フィルターにポンプなどで血液を加圧して流し込んだ場合、白血球除去フィルター材の抵抗によって生じた圧力損失によって、フィルター入口側の空間が大きく陽圧となって容器は膨らみ、溶着強度が弱い部分から該溶着部分を剥がそうとする力が常に加わり、白血球除去フィルターが破裂する可能性があった。
【０００９】
また、硬質素材容器の白血球除去フィルターでは、白血球除去フィルター材の周囲を容器の一部で圧迫して、血液が白血球除去フィルター材を通過せずに周囲を流れてしまうことを防止する構造となっていることが多い。このような構造の白血球除去フィルターでは、ポンプなどで血液を加圧し流し込むことで、フィルター入口側の空間が大きく陽圧となって容器が膨らみ、白血球除去フィルター材の周囲を圧迫している部分を、押し広げようとする力が常に加わり、白血球除去フィルター材を通過せずに周囲を流れ濾過されていない血液が流れ出てしまい、回収した血液に白血球が多く混入してしまう可能性があった。
【００１０】
濾過部断面積を拡大した硬質素材容器の白血球除去フィルターでは、これらの問題点を有するために、濾過部断面積を拡大した白血球除去フィルターには、可撓性素材を容器に用いた、可撓性の白血球除去フィルターが適している。
しかし、血液をポンプなどで加圧し濾過部断面積を拡大した可撓性容器からなる白血球除去フィルターに流し込む濾過方法を行った場合、濾過の最中に白血球除去フィルター材の抵抗によって圧力損失が生じ、フィルター入口側の空間が大きく陽圧となり容器は風船状に膨らみ、白血球除去フィルター材と容器との接合部位に、該接合を剥がそうとする力が常に加わり、白血球除去フィルターが破裂する可能性があった。
【００１１】
このような破裂を防ぐ手段の一つに、可撓性容器からなるフィルターを膨張した時の体積よりも小さい容積のプラスチック等の補強箱またはカバーに収納することにより耐圧性を高める方法が開示されている（特許文献2参照）。
しかし、本発明者がこのような補強箱に可撓性容器からなる白血球除去フィルターを収納し、血液をポンプなどで加圧し可撓性容器からなる白血球除去フィルターに流し込む濾過方法を行った場合、補強箱内部の空間の高さが、［フィルターの厚み＋５ｍｍ］未満の補強箱を使用すると、白血球除去フィルター材の抵抗によって生じる圧力損失により、白血球除去フィルター材は出口側の容器に押しつけられることになり、このような状態では、白血球除去フィルター材が出口側容器と密着し、血液の流れが阻害され、これによって白血球除去フィルター内部で血液の偏流が発生し、白血球除去能が低下してしまうことが分かった。
【００１２】
また、特許文献３には、可撓性容器からなるフィルターを硬質ホルダーに収納する発明が開示され、この硬質ホルダーでは、可撓性容器と硬質ホルダーとの癒着を防止するために、ホルダー内面に幅が１ｍｍ〜３ｍｍ、間隔が２ｍｍ〜６ｍｍ、高さ１ｍｍ〜３ｍｍのリブなどの突起状物を設けることが記載されている。しかし、本発明者がこの硬質ホルダーを使用して、ポンプなどを使用して加圧して血液を高流速で濾過しようとすると、白血球除去フィルター材が押しつけられた出口側容器は、ホルダー内面に設けられた複数のリブが作り出す隙間に膨張し進入するが、白血球除去フィルター材と出口側容器との間に血液が高流速で流れるのに十分な空間を作り出すには至らず、血液の流れが阻害されることを防ぐことが困難であることが分かった。
【００１３】
フィルターの密着を解決する方法として、フィルター材と出口側容器との間に連接棒と呼ばれる軟質塩ビチューブを挿入して密着を防ぐ方法 (特許文献４参照)や軟質容器内面に高低差0.2-2 mmの凹凸をつけて密着を防ぐ方法(特許文献５参照)、ニットファイバー製のスクリーン等を挿入する方法（特許文献６参照)等が知られている。これらの可撓性容器製白血球除去フィルターを特許文献２〜４に開示されている補強箱や硬質ホルダーやフィルタースタンド内部に配置し［フィルターの厚み＋５ｍｍ］未満の厚みとなるように体積を拘束した状態でも、ポンプなどを使用して加圧して血液を高流速で濾過した場合、白血球除去フィルター材が出口側容器と密着してしまい、白血球除去フィルター材と出口側容器との間に血液が流れるに十分な空間を作り出すには至らず、血液の流れが阻害されることを防ぐことが困難であることが分かった。
【００１４】
また、特許文献５に開示されている軟質容器内面に高低差0.2-2 mmの凹凸をつけて、白血球除去フィルター材が出口側容器と密着することを防ぐ方法においては、重力の作用によって血液製剤を濾過するといった、比較的低圧で血液を濾過した場合に、濾過時間の短縮に効果が認められるが、白血球除去能の向上には効果が現れていない。
【００１５】
一方、接合部分の耐圧性を強めた可撓性容器からなるフィルターに、血液をポンプなどで加圧し流し込む濾過方法を行った場合、白血球除去フィルター材の抵抗によって生じた圧力損失によって膨らんだフィルター入口側の空間に残留する血液を、フィルター入口側の残留圧力によって回収しようとすると、所望量の血液を回収するまでに長時間を要し、短時間で濾過を完了することが困難であった。
【００１６】
以上のように、従来の技術では、短時間で大量の血液を濾過するために、ポンプなどで加圧し可撓性容器からなる白血球除去フィルターに流し込む高流速濾過方法を行った場合、フィルターが破損する恐れや、フィルター材を通過しないで血液が流れ出てしまったり、血液の流れが阻害され偏流したりするために白血球除去能が低下したりする問題点があり、１）白血球除去能を効率よく高めること、２）血液を高効率で回収すること、を同時に達成することが困難であった。
【００１７】
【特許文献１】
特開平７−１５５３７４号公報
【特許文献２】
国際公開第９０／１５６６０号パンフレット 第６頁第１９−２５行
【特許文献３】
特開２００１−１４９４４４号公報 第7頁第１２欄第２８−５０行
【特許文献４】
欧州特許第０５２６６７８号明細書
【特許文献５】
特開平１１−２１６１７９号公報 第５頁第7欄３８行−第８欄１４行
【特許文献６】
国際公開９５／１７２３６号パンフレット
【特許文献７】
特開平７−６７９５２号公報
【特許文献８】
国際公開９７／２３２６６号パンフレット
【００１８】
【発明が解決しようとする課題】
本発明の課題は、前記のような問題点を解決することにあり、血液をポンプなどで加圧し可撓性容器からなる白血球除去フィルターに流し込む高流速濾過を行った場合、１）白血球除去能を効率よく高めること、２）血液を高効率で回収すること、を同時に達成することにある。
【００１９】
【課題を解決する手段】
本発明者は、上記課題を解決する血液濾過方法を鋭意検討した結果、可撓性容器の入口側及び出口側の外側に配置された体積拘束板を用いて白血球除去フィルターを［白血球除去フィルターの厚み＋５ｍｍ］〜［白血球除去フィルターの厚み＋３０ｍｍ］の厚みに拘束して白血球含有液を白血球除去フィルターに導入することで、白血球含有液の流速が高くなると共に白血球除去性能が向上することを見出した。
また、すべての白血球含有液が白血球除去フィルターに供給された後、リンス液を白血球除去フィルターに供給する前に、入口側に配置される体積拘束板と出口側に配置される体積拘束板の間隔を、［白血球除去フィルターの厚み−３ｍｍ］〜［白血球除去フィルターの厚み＋３ｍｍ］まで変化させ、リンス液を白血球除去フィルターに供給して、白血球除去フィルターに残留する血液を回収することによってリンス液と白血球含有液の流速を適切に調節することができ、白血球除去能及び血液回収率が向上することを見出した。
さらにまた、体積拘束板を前記第１の間隔から第２の間隔まで変化させながら白血球含有液を濾過する間の、濾過流速を適切な値に保持することによって上記課題が解決できることを見出し、本発明に至った。
【００２０】
すなわち、本発明は、入口と出口を有する可撓性容器と該容器内部を入口側と出口側とに隔てるように配置したシート状の白血球除去フィルター材からなる白血球除去フィルターに、可撓性容器の入口側および出口側の外側に配置された体積拘束板によって白血球除去フィルターの厚みを拘束しながら、白血球含有液を流す白血球含有液の濾過方法において、
（１）入口側に配置される体積拘束板と出口側に配置される体積拘束板との間隔を[白血球除去フィルターの厚み＋5mm]〜[白血球除去フィルターの厚み＋30mm]に設定して白血球含有液を白血球除去フィルターの入口から加圧して流し込む工程、
（２）体積拘束板の間隔を [白血球除去フィルターの厚み−3mm]〜[白血球除去フィルターの厚み＋3mm] まで変化させながら50ml／分以上200ml／分以下の流速で白血球含有液を濾過する工程、
（３）その後、体積拘束板の間隔 を[白血球除去フィルターの厚み−3mm]〜[白血球除去フィルターの厚み＋3mm]に固定しリンス液を白血球除去フィルターに供給して白血球除去フィルターに残留する液体を回収する工程、
からなることを特徴とする白血球含有液の濾過方法に関する。
本発明は、また、加圧しながら高流速で濾過する白血球含有液の濾過方法において好適に用いられる、向かい合う体積拘束板の間隔が可動する体積拘束板を白血球除去フィルターに組み合わせた濾過装置にも関するものである。
【００２１】
【発明の実施の形態】
以下に、本発明について詳細に述べる。
本発明で言う白血球含有液とは白血球を含有する液体であり、例えば、全血製剤、赤血球製剤、血小板製剤、血漿製剤などの白血球を含有する液体が挙げられる。
【００２２】
本発明で言う、白血球除去フィルターとは、血液の入口と出口を有する可撓性容器と、該容器内部を白血球含有液の入口側と出口側とに隔てるように配置されたシート状の白血球除去フィルター材とからなる可撓性容器製白血球除去フィルターである。例えば、前記特許文献２，４，５，７などで開示されているような従来公知の可撓性容器製白血球除去フィルターは何れも本発明に適する。
【００２３】
シート状の白血球除去フィルター材とは、メルトブロー法やフラッシュ紡糸法あるいは抄造法などによって製造された不織布等の繊維構造物や、連続した細孔を有する多孔質体（スポンジ状構造物）、多孔膜などが挙げられる。
【００２４】
フィルター材を形成する基材が繊維構造物である場合、その素材としては、ポリアミド、ポリエステル、ポリアクリロニトリル、ポリトリフルオロエチレン、ポリメチルメタアクリレート、ポリスチレン、ポリエチレン、ポリプロピレンなどが挙げられる。さらに、繊維構造物を基材とする場合、ほぼ均一な繊維径を有する繊維からなる基材であっても良いし、特許文献８に開示されているような、繊維径の異なる、複数種の繊維が混繊された形態の基材であっても良い。これらの繊維は平均繊維径が０．０１μｍ以上３．０μｍ未満であるものが望ましい。
【００２５】
フィルター材を構成する基材が多孔質体あるいは多孔膜である場合、その素材としてはポリアクリロニトリル、ポリスルホン、セルロースアセテート、ポリビニルホルマール、ポリエステル、ポリアクリレート、ポリメタクリレート、ポリウレタンなど何れの素材であっても本発明には適する。多孔質体あるいは多孔膜の平均孔径は１μｍ以上３０μｍ未満であるものが望ましい。また、フィルター材は基材そのものから構成しても良いし、その表面を化学的あるいは物理的に改質したものでも良く、何れのフィルター材も白血球除去に寄与しているシート状の白血球除去フィルター材に含まれる。
【００２６】
フィルター材は、繊維構造物、多孔質体あるいは多孔膜を単層で用いても良いし、複数層組み合わせて用いても良い。
【００２７】
本発明において、白血球含有液を白血球除去フィルターの入口から加圧して流し込み、５０ｍＬ／分以上２００ｍＬ／分以下の流速で濾過するとは、血液ポンプなどを用いて白血球含有液を加圧し、且つ流速を高めて白血球フィルターに流し込んで濾過することをいう。通常白血球除去フィルターで血液を処理する際に一般的に行われているような、処理されるべき血液製剤が入ったバッグを、フィルターよりも100cm程高い位置に置き、重力の作用によって血液製剤を濾過するといった比較的低い負荷圧力での濾過、また、流速が５０ｍＬ／分未満といった通常の血液濾過流速での濾過は、本発明における加圧して白血球含有液を高流速で濾過することとは異なる。本発明において加圧して白血球含有液を高流速で濾過するには、血液ポンプなどを白血球除去フィルターと濾過されるべき白血球含有液が入ったバッグとの間に配置し、白血球含有液を、好ましくは１００ｍｍＨｇ〜４００ｍｍＨｇの圧力で、流速５０ｍＬ／分〜２００ｍＬ／分で白血球除去フィルターに送液する。
【００２８】
流速が５０ｍＬ／分未満の低流速で濾過する場合は、所望量の血液を短時間で濾過することができないので適さない。流速が２００ｍＬ／分を超える流速で濾過する場合は、赤血球膜の破壊など有用血球成分の破壊が起こる危険性があり適さない。同様の理由から、加圧された白血球含有液の圧力は１００ｍｍＨｇ以上、４００ｍｍＨｇ以下が好ましい。
【００２９】
本発明の血液濾過方法では、白血球除去フィルターの入口側と出口側との両方に、白血球除去フィルターを挟み込むように体積拘束板を配置されることが必要である。体積拘束板には、溝や孔を設けて血液入口側及び出口側導管周囲を圧迫しない構造が好ましい。体積拘束板の白血球除去フィルターの白血球含有液入口側または出口側の外面に対向する面は、凹凸のない平面であっても良いし、断面形状が、矩形、半円、三角形などの溝や、リブや突起状物を設けた凹凸形状であっても良い。入口側と出口側の２枚の体積拘束板はほぼ平行に向き合うように、バラバラの２枚を組み合わせて用いるものが、体積拘束治具間隔を所望の間隔に調整することができるので望ましい。
【００３０】
体積拘束板の大きさは、体積拘束する白血球除去フィルターの有効濾過部分の８０％以上の面積があることが好ましい。８０％未満であると、体積拘束板からはみ出た白血球除去フィルター部分が大きく膨らみ、破裂する危険性があり好ましくない。体積拘束板の大きさが、白血球除去フィルターよりも大きい場合は、加圧によって白血球除去フィルターが大きく膨れることが回避でき、耐圧性を高めるという点でも好ましい。体積拘束板の材質は、加圧して白血球含有液を白血球除去フィルターに流し込み、高流速で濾過する場合に白血球除去フィルターが大きく膨れようとする圧力に耐え破損しない強度を保つことができれば何れの材質であっても良い。例えば、ポリカーボネート、アクリル、ポリスチレン、ポリプロピレン、硬質ポリ塩化ビニルなどの硬質プラスチック、あるいは金属などの硬質材料が挙げられる。
【００３１】
白血球含有液濾過時の入口側に使用される体積拘束板と出口側に使用される体積拘束板の間隔は、［白血球除去フィルターの厚み＋５ｍｍ］〜［白血球除去フィルターの厚み＋３０ｍｍ］であることが必要である。ここで言う白血球除去フィルターの厚みとは、血液を濾過する前の白血球除去フィルター容器の厚みを指す。入口側と出口側との体積拘束板の間隔を、［白血球除去フィルターの厚み＋５ｍｍ］よりも小さくした場合は、シート状の可撓性容器と白血球除去フィルター材との隙間が、白血球除去フィルター全体で均一にならず、隙間が他の部分よりも狭い部分が形成される。このような状態で高速で白血球含有液を流した場合、白血球含有液の流れに乱れが生じ白血球除去フィルター材全体に均等に白血球含有液が流れなくなり、白血球除去フィルター材の白血球捕捉能力を超えて白血球含有液が流れ込む部分が生じる。この結果、流速が低下したり、白血球除去性能が低下するので望ましくない。入口側と出口側との体積拘束板の間隔が、［白血球除去フィルターの厚み＋３０ｍｍ］より大きくした場合は、白血球除去フィルター内に残留する血液量が多く、赤血球保存液や生理食塩水などでリンスして回収する前に、体積拘束板の間隔を狭めて、白血球除去フィルター内に残留する血液量を少なくするのに時間を要するため望ましくない。入口側と出口側との体積拘束板の間隔が、可撓性容器からなる白血球除去フィルターの厚み＋５．５ｍｍ〜＋２５ｍｍの間隔であることがより望ましい。
【００３２】
また、本発明の濾過方法では、濾過前血液貯留バッグ内のすべての白血球含有液が白血球除去フィルターに供給された後に、好ましくは１０ｍL以上６０ｍL以下のリンス液を、流速５０ｍＬ／分〜１２０ｍＬ／分で白血球除去フィルターに供給し、白血球除去フィルターに残留する白血球含有液を回収する。リンス液を流速が５０ｍＬ／分未満の低流速で白血球除去フィルターに供給する場合は、所望量の血液を短時間で回収することができないので好ましくない。流速が１２０ｍＬ／分を超える流速でリンス液を白血球除去フィルターに供給する場合は、残留する血液と回収に使用するリンス液との混合が起こる、あるいは、血液とリンス液との粘度差が原因で回収時間内には、互いにほとんど混じり合わずに、粘度の低いリンス液が残留する血液をほとんど押し出さずにショートパスして優先的に回収されるため、血液の回収率が低下してしまい望ましくない。
【００３３】
リンス液の量が１０ｍL未満である場合、白血球除去フィルター内部に残留している血液の回収量が少ないので望ましくない。６０ｍLより多くリンス液を使用すると、回収した血液がリンス液で希釈されるので望ましくない。リンス液としては、血液にダメージを与えない溶液であれば何れも本発明には適する。例えば、濃厚赤血球を濾過する場合は、公知の赤血球保存液や生理食塩水などが適している。
【００３４】
さらに、本発明の濾過方法では、濾過前血液貯留バッグ内のすべての白血球含有液が白血球除去フィルターに供給された後に、入口側に配置される体積拘束板と出口側に配置される体積拘束板の間隔を、［白血球除去フィルターの厚み−３ｍｍ］〜［白血球除去フィルターの厚み＋３ｍｍ］まで変化させた後に、リンス液を白血球除去フィルターに供給し、白血球除去フィルターに残留する血液を回収することによって、血液回収率を高くすることができる。体積拘束板を移動させる速度は、５ｍｍ／分以上２０ｍｍ／分以下が好ましい。
【００３５】
入口側及び出口側に配置される体積拘束板の間隔を、５ｍｍ／分未満の速度で［白血球除去フィルターの厚み−３ｍｍ］〜［白血球除去フィルターの厚み＋３ｍｍ］まで狭める場合は、白血球除去フィルターの入口側の空間に残留する血液を、体積拘束板が圧迫することで出口側から押し出される際の流速が５０ｍL／分未満となり、短時間で所望の血液量を濾過し終えることができないため好ましくない。体積拘束板の間隔を、２０ｍｍ／分を超える速度で［白血球除去フィルターの厚み−３ｍｍ］〜［白血球除去フィルターの厚み＋３ｍｍ］まで狭める場合は、体積拘束板が圧迫することで出口側から押し出される際の流速が２００ｍL／分を超え、赤血球膜の破壊など有用血球成分の破壊が起こる危険性があり好ましくない。体積拘束板の間隔を［白血球除去フィルターの厚み−３ｍｍ］よりも狭めた場合は、回収時にリンス液が流れなくなるので適さない。また、体積拘束板の間隔を［白血球除去フィルターの厚み＋３ｍｍ］より広い間隔までしか狭めない場合、白血球除去フィルター内部に残留する血液とリンス液との粘度差が原因で、互いにほとんど混じり合わずに、粘度の低いリンス液が残留する血液をほとんど押し出さずにショートパスして優先的に回収されるため、血液の回収率が低下してしまい適さない。体積拘束板を５ｍｍ／分以上２０ｍｍ／分以下の速度で移動させ、流速５０ｍＬ／分〜２００ｍＬ／分で白血球含有液を濾過するためには、白血球除去フィルターの有効濾過部断面積は、２５ｃｍ２以上４００ｃｍ２以下であることが必要である。
【００３６】
次に、実施例により本発明をより詳細かつ具体的に説明するが、本発明は、これらによって範囲を限定されるものではない。
【実施例１】
血液の入口、出口を設ける部分に該入口、出口の内径と同等以上の直径を有する孔を開けた厚み0.04cmの可撓性のポリ塩化ビニル樹脂製シートと、内径3mm、外径4.2mmの塩化ビニル製のチューブを、血液の入口、出口にそれぞれ高周波溶着して、血液の入口の付いた入口側の可撓性容器、及び、血液の出口の付いた出口側の可撓性容器を作製した。
【００３７】
フィルター材として、以下に記すポリエステル製不織布を積層して用いた。平均繊維径が１２μｍ、目付が３０ｇ／ｍ２のもの（不織布（１））を４枚、平均繊維径１．７μｍ、目付が６６ｇ／ｍ２のもの（不織布（２））２枚、平均繊維径１．２μｍ、目付が４０ｇ／ｍ２のもの（不織布（３））２２枚、不織布（２）と同一のもの２枚、不織布（１）と同一のもの４枚、合計３４枚を積層したものを、この順に積層した。以上のようにして作製した、三種の不織布からなる積層物を１３０ｍｍ×１３０ｍｍ（正方形）に切断した。これらの可撓性容器と不織布の積層体とを、入口側可撓性容器、不織布の積層体、出口側可撓性容器の順に重ね合わせ、濾過部寸法が１００mm×１００ｍｍとなるように高周波溶着法を用いて可撓性容器製の白血球除去フィルターを作製した。なお、血液入口側と出口側導管は、上記正方形型白血球除去フィルターの対角線上に配置した。上記白血球除去フィルターの厚みは、９．５ｍｍであった。白血球除去フィルターの厚みの測定は次のようにして行った。白血球除去フィルターを血液出口側導管が下になるように平面板の上に置く。この時、血液出口側導管を、平板に設置した、３ｃｍ×３ｃｍ、深さ１ｃｍの窪み内に配置し、血液入口側および血液出口側導管以外の部分の白血球除去フィルター容器の厚みを測定できるようにした。平面板表面と平面板法線方向に血液入口側導管を除く白血球除去フィルターの容器の中で最も高い部分との距離を白血球除去フィルターの厚みとした。
実験に使用した不織布（２）及び（３）は、N、N−ジメチルアミノエチルメタクリレート（以下、DMと言う）と２−ヒドロキシエチルメタクリレート（以下、HEMAと言う）との共重合体（組成：DM／HEMA＝３ｍｏｌ％／９７ｍｏｌ％）を、公知の方法を使用して、コーティングしたものを使用した。コーティングした上記の共重合体の量は、不織布１ｇあたり約１０ｍｇであった。
【００３８】
上記の白血球除去フィルターを、濾過前血液貯留バッグと濾過後血液回収バッグとの間に配置し、濾過前血液貯留バッグに接続した入口側導管を白血球除去フィルターの血液入口へ、濾過後血液回収バッグに接続した出口側導管を白血球除去フィルターの血液出口へそれぞれ接続した。また、それぞれの導管として、内径3mm、外径4.2mmの塩化ビニル製のチューブを使用した。入口側導管にY字管を取付け導管を介してデジタル圧力計を取り付けた。また、濾過前血液貯留バッグとデジタル圧力計につながるY字管との間に、血液を加圧送液するための血液ポンプを取り付けた。
【００３９】
白血球除去フィルターの血液入口側及び出口側の外面に対向する体積拘束板の形状は次の通りである。１７ｃｍ×１７ｃｍのアクリル製の平面板に、４ｃｍ×４ｃｍの孔を空け血液入口側及び出口側導管周囲を圧迫しない構造とした。また、血液入口側及び出口側導管が体積拘束板によって折り曲げられたりしないように、この導管に沿って幅５ｍｍ、深さ５ｍｍの溝を設けた。
これら２枚の体積拘束板を、圧縮空気で間隔を調整することができる万力に、互いに平行かつ向かい合うように取り付け、体積拘束板同士の間隔を調整できるようにした。
上記の万力に装填した２枚の体積拘束板の間に白血球除去フィルターを配置し、体積拘束板同士の間隔が１５ｍｍ（白血球除去フィルターの厚み＋５．５ｍｍ）となるように固定した。２枚の体積拘束板で拘束した白血球除去フィルターは、血液入口側が下に、血液出口側が上になるように水平に配置して白血球含有液を濾過した。
【００４０】
４００ｍＬの牛血液に抗凝固剤として５６ｍＬの割合でＡＣＤ−Ａ液（組成：クエン酸ナトリウム２２．０ｇ／Ｌ、クエン酸８．０ｇ／Ｌ、グルコース２２．０ｇ／Ｌ）を加えて調整した全血４５６ｍＬを遠心分離した後、血漿及びバフィーコートを除去し、赤血球保存液（組成：グルコース２２．００ｇ／Ｌ、塩化ナトリウム９．００ｇ／Ｌ、アデニン０．２７ｇ／Ｌ、マンニトール７．５０ｇ／Ｌ）を加えた濃厚赤血球製剤（ヘマトクリットは約６４％）を調整し、２０℃で２０時間保存したものを複数準備し、白血球含有液として使用した。
【００４１】
上記の白血球除去フィルターに、濃厚赤血球製剤７２１ｇを、血液ポンプを使って３００ｍｍＨｇに加圧して流し込み濾過することにより白血球除去性能を評価した。濾過前血液貯留バッグ内の濃厚赤血球製剤がなくなるまで血液ポンプを使って血液を白血球除去フィルターに供給し続けた。流量は１１２ｍL／分であった。その後一旦、白血球除去フィルターと濾過前血液貯留バッグとの間の導管を遮断した。この操作に引き続いて、１０ｍｍ／分の移動速度で、９．５ｍｍ（白血球除去フィルターの厚み＋０ｍｍ）に到達するまで等速度で２枚の向かい合う体積拘束板の間隔を狭めた。このときの流量は７８ｍL／分であった。その後リンス液として３０ｍＬの生理食塩水を血液ポンプを使用して３００ｍｍＨｇに加圧して白血球除去フィルターに流し込み濾過した血液を回収した。また、血液出口側導出管からリンス液が流出した時点で導管を遮断し回収を終了した。この時の流量は８０ｍL／分であった。濾過前の濃厚赤血球製剤（以下、濾過前液と言う）、及び回収された濃厚赤血球製剤（以下、回収液と言う）の白血球濃度を求め、これによって白血球除去能を求めた。
【００４２】
濾過前液の白血球濃度は、チュルク液によって１０倍希釈し、ビルケルチュルク型の血球計算盤に注入して、光学顕微鏡を用いて白血球数をカウントすることによって測定した。
また、回収液の白血球濃度の測定は、以下に示す方法によって行った。回収液１ｍLを、リューコプレート液（ＳＯＢＩＯＤＡ社製）にて１０倍希釈する。希釈液をよく混和した後、室温にて６〜１０分間放置した。これを、２，７５０ｇで７分間遠心し、上清を除去して液量を１．０２ｇに調整した。この試料液をよく混和した後、ナジェット型の血球計算盤に注入し、光学顕微鏡を用いて白血球数をカウントすることによって白血球濃度を測定した。
【００４３】
濾過前液の濃厚赤血球製剤重量（白血球含有液重量）と、濾過後の回収液重量から下記式（１）により赤血球回収率を求めた。
赤血球回収率（％）＝１００×（回収液重量×回収液のヘマトクリット値）／（濾過前白血球含有液重量×濾過前液のヘマトクリット値）・・・・（１）
【００４４】
白血球除去フィルター入口側のフィルター材に濃厚赤血球製剤が到達した時点から、入口側に配置される体積拘束板と出口側に配置される体積拘束板との間隔を変化させる直前までを濾過１、体積拘束板の間隔を変化させ始めて、それらの間隔が所望の間隔に到達するまでを濾過２、さらに白血球除去フィルターへのリンス液の注入開始時点から、出口側導出管からの回収液の流出速度が５０ｍL／分になるまでを濾過３と区分し、各濾過区分における濾過時間と回収液の重量をそれぞれ計測した。流速は、回収液重量に濃厚赤血球製剤の比重として１．０８を乗じ、これを濾過時間で除して算出した。
【００４５】
【実施例２】
濾過１開始時に、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定した以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過１における体積拘束板同士の間隔を、実施例１よりも２０ｍｍ広く、３５ｍｍに設定することで、白血球除去能が更に向上した。
【００４６】
【比較例１】
濾過１開始時に、２枚の体積拘束板同士の間隔を１０．５ｍｍに（白血球除去フィルターの厚み＋１．０ｍｍ）設定した以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過１開始時に、白血球除去フィルターに濾過前血液が流し込まれる様子を観察したところ、偏流が観察され白血球除去フィルター材全体に血液が均一に流れていないことがわかった。回収液中の残存白血球濃度は、実施例１の２．３倍と多かった。また、濾過１における流速１は４０ｍＬ／分と小さかった。
【００４７】
【比較例２】
濾過開始時に、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、回収時に２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定、すなわちリンス液を白血球除去フィルターに流し込む時（濾過３）に体積拘束板の間隔を変化させずに血液を回収した。この操作以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過３において白血球除去フィルターにリンス液を流し込むと、白血球除去フィルター内部に残留している血液と、ほとんど混じり合わずに通過し出口側導出管から排出された。白血球除去フィルター内部に残留している血液が多く、赤血球回収率は８１％と低かった。
【００４８】
実施例１、実施例２、比較例１および比較例２はそれぞれ同一の濃厚赤血球製剤、すなわち、一旦プールした血液を分割して濾過に使用し、同一の濃厚赤血球製剤を使用して実施例１、実施例２、比較例１および比較例２を一組にして評価した。
濾過前液の白血球濃度は、５，０００から１０，０００個／μＬの範囲であった。回収液中の残存白血球濃度を実施例１の結果を基準にして相対評価し白血球除去能を比較した。また、流速、赤血球回収率と共に結果を表１にまとめた。
【００４９】
【表１】
次に、濾過３における体積拘束治具間隔を変化させて、濾過を行った実施例および比較例について説明する。
【実施例３】
濾過開始時に、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、回収時に２枚の体積拘束板同士の間隔を７．５ｍｍ（白血球除去フィルターの厚み−２．０ｍｍ）に設定した以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
【００５１】
【実施例４】
濾過開始時に、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、回収時に２枚の体積拘束板同士の間隔を１２．５ｍｍ（白血球除去フィルターの厚み＋３．０ｍｍ）に設定した以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
【００５２】
【比較例３】
濾過開始時に、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、回収時に２枚の体積拘束板同士の間隔を５．５ｍｍ（白血球除去フィルターの厚み−４．０ｍｍ）に設定した以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過３の体積拘束板の間隔を５．５ｍｍに設定、すなわちフィルターの厚みを４ｍｍ圧縮したため抵抗が大きくなり、リンス液は白血球除去フィルターを流れなかった。従って流速３および赤血球回収率を算出することができなかった。また、回収液中の残存白血球濃度は、実施例３に比べて多く、極度に白血球除去フィルターを圧縮したことで、一旦捕捉した白血球が漏出したと考えられる。
【００５３】
【比較例４】
濾過開始時に、２枚の体積拘束板同士の間隔を３５ｍｍに（白血球除去フィルターの厚み＋２５．５ｍｍ）設定し、濾過３における２枚の体積拘束板同士の間隔を１４．５ｍｍ（白血球除去フィルターの厚み＋５．０ｍｍ）に設定した以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過３において白血球除去フィルターにリンス液を流し込むと、白血球除去フィルター内部に残留している血液とほとんど混じり合わずに通過し、出口側導出管から排出された。白血球除去フィルター内部に残留している血液が多く、赤血球回収率は８６％と低かった。
【００５４】
実施例３、実施例４、比較例３および比較例４はそれぞれ同一の濃厚赤血球製剤、すなわち、一旦プールした血液を分割して濾過に使用し、同一の濃厚赤血球製剤を使用して実施例３、実施例４、比較例３および比較例４を一組にして評価した。
濾過前液の白血球濃度は、５，０００から１０，０００個／μＬの範囲であった。回収液中の残存白血球濃度を実施例３の結果を基準にして相対評価し白血球除去能を比較した。また、流速、赤血球回収率と共に結果を表２にまとめた。
【００５５】
【表２】
次に、濾過２において、体積拘束治具間隔の変化速度を変えて評価した実施例および比較例について説明する。
【実施例５】
濾過１において、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、濾過２において５．０ｍｍ／分の速度で２枚の体積拘束板同士の間隔を９．５ｍｍ（白血球除去フィルターの厚み＋０ｍｍ）まで狭めた以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
【００５７】
【実施例６】
濾過１において、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、濾過２において１８ｍｍ／分の速度で２枚の体積拘束板同士の間隔を９．５ｍｍ（白血球除去フィルターの厚み＋０ｍｍ）まで狭めた以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
【００５８】
【比較例５】
濾過１において、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、濾過２において２．０ｍｍ／分の速度で２枚の体積拘束板同士の間隔を９．５ｍｍ（白血球除去フィルターの厚み＋０ｍｍ）まで狭めた以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過２において体積拘束治具間隔を狭める速度が遅く、この時の流速が遅くなったために、流速２が２２ｍL／分と小さくなった。
【００５９】
【比較例６】
濾過１において、２枚の体積拘束板同士の間隔を３５ｍｍ（白血球除去フィルターの厚み＋２５．５ｍｍ）に設定し、濾過２において２２ｍｍ／分の速度で２枚の体積拘束板同士の間隔を９．５ｍｍ（白血球除去フィルターの厚み＋０ｍｍ）まで狭めた以外は、実施例１と同じ白血球除去フィルターを使用し、同一の操作を行った。
濾過２において体積拘束治具間隔を狭める速度が速く、この時白血球除去フィルターに加わる圧力が５００ｍｍHgを超え極度の溶血が観察された。比較例６以外の実施例および比較例では、回収液のヘマトクリット値に変化が見られなかったが、比較例６では、濾過前血液のヘマトクリット値が６４％であったのに対して、回収液のヘマトクリット値は６２％と低く、赤血球回収率は８７％と低くなった。また、流速２が２００ｍＬ／分を超えて速くなったために、一旦白血球除去フィルター材に捕捉された白血球が漏出したと考えられた。回収液中の残存白血球濃度は、実施例５の１．７倍と多かった。
【００６０】
実施例５、実施例６、比較例５および比較例６はそれぞれ同一の濃厚赤血球製剤、すなわち、一旦プールした血液を分割して濾過に使用し、同一の濃厚赤血球製剤を使用して実施例５、実施例６、比較例５および比較例６を一組にして評価した。
濾過前液の白血球濃度は、５，０００から１０，０００個／μＬの範囲であった。回収液中の残存白血球濃度を実施例５の結果を基準にして相対評価し白血球除去能を比較した。また、流速、赤血球回収率と共に結果を表３にまとめた。
【００６１】
【表３】
【発明の効果】
以上の通り、本発明の濾過方法、体積拘束板及び濾過装置によれば、１）白血球除去能を効率よく高めること、２）血液を高効率で回収すること、を同時に達成することができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for filtering a leukocyte-containing liquid using a leukocyte removal filter for removing undesirable components such as aggregates and leukocytes from the leukocyte-containing liquid, and an apparatus therefor. In particular, when filtering leukocyte-containing liquid at a high flow rate using a pump or the like using a leukocyte removal filter consisting of a flexible container, the leukocyte removal filter is prevented from bulging and the leukocyte removal filter thickness is appropriately adjusted. It relates to filtration using a volume constraining plate for holding and making the flow uniform.
[0002]
[Prior art]
In the field of blood transfusion, so-called leukocyte-removed blood transfusion, in which a blood product is transfused after removing contaminating leukocytes contained in the blood product, has become widespread. This includes relatively minor side effects such as headache, nausea, chills, and non-hemolytic fever reactions associated with blood transfusions, and severe allergies such as alloantigen sensitization, virus infection, and post-transfusion GVHD. This is because it has been clarified that such side effects are mainly caused by leukocytes mixed in blood products used for blood transfusion.
[0003]
The leukocyte removal method is roughly divided into a centrifuge method that separates and removes leukocytes using the difference in specific gravity of blood components using a centrifuge, and a porous element such as a fiber material or a porous body having continuous pores. There are two types of filter methods that remove leukocytes using a filter material comprising: The filter method is currently popular because it has advantages such as excellent leukocyte removal ability, simple operation, and low cost.
[0004]
The filtration method, that is, the treatment of leukocyte-containing liquids such as blood products with a leukocyte removal filter was often carried out at the bedside during blood transfusion operations, but in recent years, quality control of leukocyte removal blood products and leukocyte removal In order to improve the effectiveness of the treatment, it is becoming common for blood centers to be performed before storage.
[0005]
Conventional leukocyte removal filters have been widely used in which filter elements made of non-woven fabric or porous material are packed in a hard container such as polycarbonate.
1) Since the container does not have water vapor permeability, it is difficult to apply high-pressure steam sterilization, which is widely used as a sterilization process for blood collection and separation set.
2) When using a so-called closed system in which a leukocyte removal filter is incorporated in the blood collection separation set and separating the whole blood into a plurality of blood components by centrifugation, the leukocyte removal filter is used together with the blood collection separation set. Since it is centrifuged, the hard container may damage the bag or the conduit, or the hard container itself may not withstand the stress during centrifugation and may be damaged.
In order to solve these problems, a flexible leukocyte removal filter using a flexible material for a container has been developed.
[0006]
Normally, when filtering blood with these leukocyte removal filters, it is common to place the bag containing the blood product to be filtered at a position about 100 cm higher than the filter and filter the blood product by the action of gravity. is there.
However, in recent years, as a demand for leukocyte removal filters, there is a demand for processing a desired amount of blood in a short time to shorten the working time.
[0007]
On the other hand, the declining birthrate and aging population are progressing in developed countries in recent years, and the blood donable population is decreasing. There is concern that the number of blood donors will decrease as the population that can donate blood decreases, and that the shortage of blood necessary for blood transfusion will become a serious problem in the near future. In order to avoid such problems, it has been studied to collect a large amount of blood from a single blood donor and to secure blood necessary for transfusion. In this case, a large amount of blood is filtered at a time, specifically 1.5 to 2 times the conventional blood, and a large amount of blood is filtered in a short time to shorten the working time. There is also a demand for it.
For this reason, in addition to the conventional method of filtering blood products by the action of gravity, the blood to be filtered is pressurized by a pump or the like and poured into a leukocyte removal filter to increase the blood filtration rate. Methods for filtering blood over time are being considered.
[0008]
In the prior art, as a technical means for filtering a large amount of blood in a short time to shorten the working time, it is conceivable to increase the cross-sectional area of the filtration part of the leukocyte removal filter. For applications where a blood collection / separation set incorporating a leukocyte removal filter is not centrifuged, it is conceivable to use a leukocyte removal filter of a hard material container with an enlarged cross-sectional area of the filtration part (see Patent Document 1). However, in the leukocyte removal filter of the hard material container having an enlarged cross-sectional area of the filtration part, it is difficult to weld uniformly over the entire circumference of the container, and a part having a weak welding strength is partially formed. When blood is pumped into such a leukocyte removal filter and flowed in, the pressure loss caused by the resistance of the leukocyte removal filter material results in a large positive pressure on the filter inlet side, causing the container to swell and weld strength There was a possibility that the leukocyte removal filter could be ruptured by constantly applying a force to peel the welded part from the weak part.
[0009]
In addition, the leukocyte removal filter of the hard material container has a structure that presses the periphery of the leukocyte removal filter material with a part of the container to prevent blood from flowing around without passing through the leukocyte removal filter material. There are many. In the leukocyte removal filter having such a structure, when the blood is pressurized and poured with a pump or the like, the space on the filter inlet side becomes a large positive pressure and the container swells, and the portion that presses around the leukocyte removal filter material is removed. However, there is a possibility that a force to spread is constantly applied, blood that does not pass through the leukocyte-removing filter material flows through the surroundings and flows out and is not filtered, and a lot of white blood cells are mixed in the collected blood.
[0010]
The leukocyte removal filter with a hard material container with an enlarged cross-sectional area of the filtration part has these problems. Therefore, the leukocyte removal filter with an enlarged cross-sectional area of the filtration part uses a flexible material for the container. Sex leukocyte removal filters are suitable.
However, when a filtration method is used in which blood is pressurized with a pump and poured into a leukocyte removal filter consisting of a flexible container with an enlarged cross-sectional area of the filtration part, pressure loss occurs due to the resistance of the leukocyte removal filter material during filtration. There is a possibility that the space at the filter inlet side becomes a large positive pressure and the container swells like a balloon, and the leukocyte removal filter is ruptured by constantly applying a force to peel off the bond at the junction between the leukocyte removal filter material and the container. was there.
[0011]
As one of means for preventing such bursting, a method of increasing pressure resistance by housing a filter made of a flexible container in a reinforcing box or cover made of plastic or the like having a volume smaller than the volume when expanded is disclosed. (See Patent Document 2).
However, when the present inventor houses a leukocyte removal filter made of a flexible container in such a reinforcing box and performs a filtration method in which blood is pressurized with a pump or the like and poured into the leukocyte removal filter made of a flexible container, When using a reinforcing box whose height of the space inside the reinforcing box is less than [filter thickness + 5 mm], the leukocyte removing filter material is pressed against the outlet side container due to pressure loss caused by the resistance of the leukocyte removing filter material. Thus, in such a state, the leukocyte removal filter material is in close contact with the outlet-side container, and the blood flow is inhibited, thereby causing a blood drift inside the leukocyte removal filter and reducing the leukocyte removal ability. I understood.
[0012]
Patent Document 3 discloses an invention in which a filter made of a flexible container is stored in a hard holder. In this hard holder, in order to prevent adhesion between the flexible container and the hard holder, It is described that protrusions such as ribs having a width of 1 mm to 3 mm, an interval of 2 mm to 6 mm, and a height of 1 mm to 3 mm are provided. However, when the present inventor uses this hard holder to pressurize the blood using a pump or the like to filter blood at a high flow rate, the outlet side container on which the leukocyte removal filter material is pressed is provided on the inner surface of the holder. However, it does not lead to a sufficient space for blood to flow at a high flow rate between the leukocyte removal filter material and the outlet side container, and the blood flow is hindered. It turned out to be difficult to prevent.
[0013]
As a method of solving the close contact of the filter, a method of preventing the close contact by inserting a soft PVC tube called a connecting rod between the filter material and the outlet side container (see Patent Document 4), or a height difference of 0.2-2 on the inner surface of the soft container There are known a method for preventing the adhesion by providing unevenness of mm (see Patent Document 5), a method for inserting a screen made of knit fiber or the like (see Patent Document 6), and the like. These flexible container-made leukocyte removal filters were placed inside the reinforcing box, hard holder, or filter stand disclosed in Patent Documents 2 to 4, and the volume was restricted so that the thickness was less than [filter thickness + 5 mm]. Even in the state, when blood is filtered at a high flow rate using a pump or the like, the leukocyte-removing filter material adheres to the outlet-side container, and the blood flows between the leukocyte-removing filter material and the outlet-side container. However, it was found that it was difficult to prevent the blood flow from being obstructed.
[0014]
Further, in the method disclosed in Patent Document 5 in which the inner surface of the soft container is provided with irregularities with a height difference of 0.2-2 mm to prevent the leukocyte-removing filter material from coming into close contact with the outlet-side container, the blood product is produced by the action of gravity. When blood is filtered at a relatively low pressure, such as filtration, an effect is observed in shortening the filtration time, but no effect appears in improving the leukocyte removal ability.
[0015]
On the other hand, when a filtration method in which blood is pressurized with a pump or the like and poured into a filter made of a flexible container with increased pressure resistance at the joint, the filter inlet swelled due to pressure loss caused by the resistance of the leukocyte removal filter material When the blood remaining in the side space is to be collected by the residual pressure on the filter inlet side, it takes a long time to collect a desired amount of blood, and it is difficult to complete the filtration in a short time.
[0016]
As described above, in the conventional technique, in order to filter a large amount of blood in a short time, when a high flow rate filtration method in which pressure is applied with a pump or the like and poured into a leukocyte removal filter made of a flexible container is used, the filter is damaged. There is a problem that the blood flows out without passing through the filter material, or the blood flow is obstructed and drifts and the leukocyte removing ability is reduced. It has been difficult to simultaneously increase and 2) recover blood with high efficiency.
[0017]
[Patent Document 1]
JP-A-7-155374
[Patent Document 2]
International Publication No. 90/15660 pamphlet, page 6, lines 19-25
[Patent Document 3]
JP 2001-149444 A, page 7, column 12, lines 28-50
[Patent Document 4]
European Patent No. 0526678
[Patent Document 5]
JP 11-216179 A, page 5, column 7, line 38-column 8, line 14
[Patent Document 6]
International Publication No. 95/17236 Pamphlet
[Patent Document 7]
JP-A-7-67952
[Patent Document 8]
WO 97/23266 pamphlet
[0018]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems. When high-flow rate filtration is performed in which blood is pressurized with a pump or the like and poured into a leukocyte removal filter formed of a flexible container, 1) leukocyte removal ability And 2) to collect blood with high efficiency at the same time.
[0019]
[Means for solving the problems]
As a result of intensive studies on a blood filtration method for solving the above-described problems, the present inventor conducted a leukocyte removal filter using a volume constraining plate disposed outside the inlet side and the outlet side of the flexible container. It was found that the leukocyte-containing liquid was introduced into the leukocyte removal filter while being restricted by the thickness of [thickness + 5 mm] to [thickness of leukocyte removal filter + 30 mm], and the leukocyte removal performance was improved while the flow rate of the leukocyte-containing liquid was increased. .
In addition, after all the leukocyte-containing liquid is supplied to the leukocyte removal filter, before the rinse solution is supplied to the leukocyte removal filter, the interval between the volume restriction plate arranged on the inlet side and the volume restriction plate arranged on the outlet side Is changed from [leukocyte removal filter thickness-3 mm] to [leukocyte removal filter thickness + 3 mm], supplying the rinsing liquid to the leukocyte removal filter, and recovering the blood remaining in the leukocyte removal filter, It has been found that the flow rate of the leukocyte-containing liquid can be adjusted appropriately, and the leukocyte removal ability and blood recovery rate are improved.
Furthermore, the present inventors have found that the above problem can be solved by maintaining the filtration flow rate at an appropriate value while filtering the leukocyte-containing liquid while changing the volume restricting plate from the first interval to the second interval. Invented.
[0020]
That is, the present invention relates to a leukocyte removal filter comprising a flexible container having an inlet and an outlet and a sheet-like leukocyte removal filter material arranged so that the inside of the container is separated from the inlet side and the outlet side. In the method for filtering a leukocyte-containing liquid in which the leukocyte-containing liquid is allowed to flow while restricting the thickness of the leukocyte removal filter by a volume constraining plate disposed on the outside of the inlet side and the outlet side of
(1) A white blood cell-containing liquid in which the distance between the volume restricting plate disposed on the inlet side and the volume restricting plate disposed on the outlet side is set to [thickness of leukocyte removal filter + 5 mm] to [thickness of leukocyte removal filter + 30 mm]. Pressurizing and flowing from the inlet of the leukocyte removal filter,
(2) The step of filtering the leukocyte-containing solution at a flow rate of 50 ml / min to 200 ml / min while changing the interval between the volume restraint plates from [leukocyte removal filter thickness-3 mm] to [leukocyte removal filter thickness + 3 mm],
(3) Thereafter, the interval between the volume restraint plates is fixed at [thickness of leukocyte removal filter−3 mm] to [thickness of leukocyte removal filter + 3 mm], and the rinse solution is supplied to the leukocyte removal filter to remove the liquid remaining on the leukocyte removal filter. Recovering process,
The present invention relates to a method for filtering a leukocyte-containing solution.
The present invention also relates to a filtration apparatus that is combined with a leukocyte removal filter, which is suitably used in a method for filtering a leukocyte-containing solution that is filtered at a high flow rate while being pressurized, and in which a volume restraint plate in which the distance between opposing volume restraint plates is movable is combined. Is.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The leukocyte-containing liquid referred to in the present invention is a liquid containing leukocytes, and examples thereof include liquids containing leukocytes such as whole blood preparations, erythrocyte preparations, platelet preparations and plasma preparations.
[0022]
The leukocyte removal filter referred to in the present invention is a flexible container having a blood inlet and outlet, and a sheet-like leukocyte removal arranged so that the inside of the container is separated from the inlet side and the outlet side of the leukocyte-containing liquid. A leukocyte removal filter made of a flexible container made of a filter material. For example, any conventionally known leukocyte removal filter made of a flexible container as disclosed in Patent Documents 2, 4, 5, and 7 is suitable for the present invention.
[0023]
Sheet-like leukocyte-removing filter materials include fiber structures such as nonwoven fabrics produced by the melt-blowing method, flash spinning method, papermaking method, etc., porous bodies having continuous pores (sponge-like structures), porous membranes Etc.
[0024]
When the base material forming the filter material is a fiber structure, examples of the material include polyamide, polyester, polyacrylonitrile, polytrifluoroethylene, polymethyl methacrylate, polystyrene, polyethylene, and polypropylene. Furthermore, when the fiber structure is used as a base material, it may be a base material made of fibers having a substantially uniform fiber diameter, or a plurality of types having different fiber diameters as disclosed in Patent Document 8. A base material in a form in which fibers are mixed may be used. These fibers preferably have an average fiber diameter of 0.01 μm or more and less than 3.0 μm.
[0025]
When the base material constituting the filter material is a porous body or a porous membrane, the material may be any material such as polyacrylonitrile, polysulfone, cellulose acetate, polyvinyl formal, polyester, polyacrylate, polymethacrylate, polyurethane, etc. Suitable for the present invention. The average pore diameter of the porous body or porous membrane is preferably 1 μm or more and less than 30 μm. In addition, the filter material may be composed of the base material itself, or the surface thereof may be chemically or physically modified, and any filter material contributes to the removal of leukocytes. Included in the material.
[0026]
As the filter material, a fiber structure, a porous body or a porous film may be used as a single layer, or a plurality of layers may be used in combination.
[0027]
In the present invention, the leukocyte-containing liquid is pressurized and poured from the inlet of the leukocyte removal filter and filtered at a flow rate of 50 mL / min to 200 mL / min. It refers to raising and pouring into a leukocyte filter and filtering. Place the bag containing the blood product to be processed, which is generally used when processing blood with a leukocyte removal filter, at a position about 100 cm higher than the filter, and remove the blood product by the action of gravity. Filtration at a relatively low load pressure, such as filtration, and filtration at a normal blood filtration flow rate, such as a flow rate of less than 50 mL / min, are different from pressurizing and filtering a leukocyte-containing solution at a high flow rate in the present invention. . In order to filter the leukocyte-containing liquid under high pressure in the present invention, a blood pump or the like is disposed between the leukocyte removal filter and the bag containing the leukocyte-containing liquid to be filtered, and the leukocyte-containing liquid is preferably used. Is sent to the leukocyte removal filter at a flow rate of 50 mL / min to 200 mL / min at a pressure of 100 mmHg to 400 mmHg.
[0028]
When filtering at a low flow rate of less than 50 mL / min, it is not suitable because a desired amount of blood cannot be filtered in a short time. When filtration is performed at a flow rate exceeding 200 mL / min, there is a risk of destruction of useful blood cell components such as erythrocyte membrane destruction, which is not suitable. For the same reason, the pressure of the pressurized leukocyte-containing liquid is preferably 100 mmHg or more and 400 mmHg or less.
[0029]
In the blood filtration method of the present invention, it is necessary to dispose a volume constraining plate so as to sandwich the leukocyte removal filter on both the inlet side and the outlet side of the leukocyte removal filter. The volume constraining plate preferably has a structure in which grooves and holes are provided so as not to press around the blood inlet side and outlet side conduits. The surface facing the outer surface of the leukocyte-containing liquid inlet side or outlet side of the leukocyte removal filter of the volume restraint plate may be a flat surface without unevenness, and the cross-sectional shape is a groove such as a rectangle, a semicircle, a triangle, An uneven shape provided with ribs or protrusions may be used. It is desirable that the two volume constraining plates on the inlet side and the outlet side are used in combination so that the two volume constraining plates face each other substantially in parallel, because the volume constraining jig interval can be adjusted to a desired interval.
[0030]
The size of the volume restricting plate is preferably 80% or more of the effective filtration portion of the leukocyte removal filter that restricts the volume. If it is less than 80%, the leukocyte removal filter portion that protrudes from the volume constraining plate swells greatly and may rupture, which is not preferable. When the size of the volume constraining plate is larger than that of the leukocyte removal filter, it is possible to prevent the leukocyte removal filter from being greatly swollen by pressurization, which is preferable in terms of enhancing pressure resistance. The material of the volume constraining plate can be any material as long as it can withstand the pressure that the leukocyte removal filter swells greatly when it is pressurized and poured into the leukocyte removal filter and filtered at a high flow rate, and does not break. It may be. For example, a hard material such as polycarbonate, acrylic, polystyrene, polypropylene, hard plastic such as hard polyvinyl chloride, or metal can be used.
[0031]
The distance between the volume restricting plate used on the inlet side and the volume restricting plate used on the outlet side during filtration of the leukocyte-containing liquid may be [leukocyte removal filter thickness + 5 mm] to [leukocyte removal filter thickness + 30 mm]. is necessary. The thickness of the leukocyte removal filter here refers to the thickness of the leukocyte removal filter container before the blood is filtered. When the distance between the volume restricting plate on the inlet side and the outlet side is smaller than [thickness of leukocyte removal filter + 5 mm], the gap between the sheet-like flexible container and the leukocyte removal filter material is the entire leukocyte removal filter. Therefore, a portion where the gap is narrower than other portions is formed. When the leukocyte-containing liquid is flowed at a high speed in such a state, the flow of the leukocyte-containing liquid is disturbed, and the leukocyte-containing liquid does not flow evenly throughout the leukocyte removal filter material, exceeding the leukocyte capture ability of the leukocyte removal filter material. A part into which the leukocyte-containing liquid flows is generated. As a result, the flow rate is lowered and the leukocyte removal performance is lowered, which is not desirable. If the distance between the volume restricting plates on the inlet side and the outlet side is greater than [thickness of leukocyte removal filter + 30 mm], the amount of blood remaining in the leukocyte removal filter is large, and rinse with erythrocyte preservation solution or physiological saline. Therefore, it is not desirable because it takes time to reduce the volume of blood remaining in the leukocyte removal filter by narrowing the interval between the volume constraining plates before recovery. More preferably, the interval between the volume restricting plates on the inlet side and the outlet side is an interval of the thickness of the leukocyte removal filter made of a flexible container +5.5 mm to +25 mm.
[0032]
In the filtration method of the present invention, after all the leukocyte-containing liquid in the pre-filtration blood storage bag is supplied to the leukocyte removal filter, a rinse liquid of preferably 10 mL to 60 mL is preferably flowed at a flow rate of 50 mL / min to 120 mL / min. To supply the leukocyte removal filter and collect the leukocyte-containing liquid remaining on the leukocyte removal filter. When the rinse solution is supplied to the leukocyte removal filter at a low flow rate of less than 50 mL / min, it is not preferable because a desired amount of blood cannot be collected in a short time. When supplying the rinsing solution to the leukocyte removal filter at a flow rate exceeding 120 mL / min, mixing of the remaining blood with the rinsing solution used for recovery occurs, or due to the difference in viscosity between the blood and the rinsing solution. Within the collection time, the rinsing liquids with little viscosity are not mixed with each other, and the remaining blood is preferentially collected through a short pass without almost pushing out the blood, which undesirably reduces the blood recovery rate. .
[0033]
If the amount of the rinsing solution is less than 10 mL, it is not desirable because the amount of collected blood remaining in the leukocyte removal filter is small. Use of more than 60 mL of rinsing solution is undesirable because the collected blood is diluted with the rinsing solution. Any rinse solution that does not damage blood is suitable for the present invention. For example, when filtering concentrated red blood cells, a known red blood cell preservation solution or physiological saline is suitable.
[0034]
Further, in the filtration method of the present invention, after all the leukocyte-containing liquid in the pre-filtration blood storage bag is supplied to the leukocyte removal filter, the volume restraint plate disposed on the inlet side and the volume restraint plate disposed on the outlet side. By changing the interval from [leukocyte removal filter thickness-3 mm] to [leukocyte removal filter thickness + 3 mm], then supplying a rinse solution to the leukocyte removal filter and collecting the blood remaining in the leukocyte removal filter The blood recovery rate can be increased. The moving speed of the volume constraining plate is preferably 5 mm / min or more and 20 mm / min or less.
[0035]
When the interval between the volume restricting plates arranged on the inlet side and the outlet side is narrowed from [leukocyte removal filter thickness-3 mm] to [leukocyte removal filter thickness + 3 mm] at a speed of less than 5 mm / min, Since the blood remaining in the inlet side space is pushed from the outlet side by pressing the volume restraining plate, the flow rate becomes less than 50 mL / min, and it is not preferable because the desired blood volume cannot be completely filtered in a short time. . When the interval between the volume constraining plates is narrowed from [Leukocyte removal filter thickness-3 mm] to [Leukocyte removal filter thickness + 3 mm] at a speed exceeding 20 mm / min, the volume constraining plate is pushed out from the outlet side by being compressed. The flow rate exceeds 200 mL / minute, and there is a risk that destruction of useful blood cell components such as destruction of the erythrocyte membrane may occur. If the interval between the volume constraining plates is narrower than [thickness of leukocyte removal filter-3 mm], the rinsing liquid does not flow at the time of recovery, which is not suitable. In addition, when the interval between the volume restraint plates can be narrowed only to an interval larger than [thickness of leukocyte removal filter + 3 mm], it hardly mixes with each other due to the difference in viscosity between the blood remaining in the leukocyte removal filter and the rinse solution. Since the rinse liquid with low viscosity is preferentially collected through a short pass without almost extruding the remaining blood, the blood recovery rate is not suitable. In order to move the volume constraining plate at a speed of 5 mm / min to 20 mm / min and filter the leukocyte-containing liquid at a flow rate of 50 mL / min to 200 mL / min, the effective filtration cross-sectional area of the leukocyte removal filter is 25 cm. 2 More than 400cm 2 It is necessary that:
[0036]
EXAMPLES Next, although an Example demonstrates this invention in detail and specifically, this invention is not limited by these.
[Example 1]
A flexible polyvinyl chloride resin sheet having a thickness of 0.04 cm, with a hole having a diameter equal to or larger than the inner diameter of the inlet and outlet at the blood inlet and outlet, and an inner diameter of 3 mm and an outer diameter of 4.2 mm A vinyl chloride tube is radio frequency welded to the blood inlet and outlet to produce a flexible container on the inlet side with a blood inlet and a flexible container on the outlet side with a blood outlet. did.
[0037]
As a filter material, a polyester nonwoven fabric described below was laminated and used. The average fiber diameter is 12 μm, and the basis weight is 30 g / m. 2 (Nonwoven fabric (1)), average fiber diameter 1.7 μm, basis weight 66 g / m 2 (Nonwoven fabric (2)), average fiber diameter 1.2 μm, basis weight 40 g / m 2 22 sheets (nonwoven fabric (3)), 2 sheets identical to the nonwoven fabric (2), 4 sheets identical to the nonwoven fabric (1), a total of 34 sheets were laminated in this order. The laminate made of the three types of nonwoven fabrics produced as described above was cut into 130 mm × 130 mm (square). These flexible containers and a laminate of nonwoven fabric are superposed in the order of an inlet side flexible container, a nonwoven fabric laminate, and an outlet side flexible container, and high-frequency welding is performed so that the size of the filtration part is 100 mm × 100 mm. Using the method, a leukocyte removal filter made of a flexible container was prepared. The blood inlet side and outlet side conduits were arranged on the diagonal line of the square leukocyte removal filter. The leukocyte removal filter had a thickness of 9.5 mm. The thickness of the leukocyte removal filter was measured as follows. Place the leukocyte removal filter on the flat plate with the blood outlet conduit down. At this time, the blood outlet side conduit is placed in a recess of 3 cm × 3 cm and 1 cm deep installed on a flat plate so that the thickness of the leukocyte removal filter container other than the blood inlet side and the blood outlet side conduit can be measured. I made it. The distance between the flat plate surface and the highest portion of the leukocyte removal filter container excluding the blood inlet side conduit in the normal direction of the flat plate was taken as the leukocyte removal filter thickness.
Nonwoven fabrics (2) and (3) used in the experiment were a copolymer (composition: N, N-dimethylaminoethyl methacrylate (hereinafter referred to as DM) and 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA). DM / HEMA = 3 mol% / 97 mol%) was coated using a known method. The amount of the above coated copolymer was about 10 mg per 1 g of the nonwoven fabric.
[0038]
The leukocyte removal filter is disposed between the pre-filtration blood storage bag and the post-filtration blood collection bag, and the inlet side conduit connected to the pre-filtration blood storage bag is connected to the blood inlet of the leukocyte removal filter. Were connected to the blood outlet of the leukocyte removal filter. As each conduit, a polyvinyl chloride tube having an inner diameter of 3 mm and an outer diameter of 4.2 mm was used. A Y-tube was attached to the inlet side conduit, and a digital pressure gauge was attached via the conduit. In addition, a blood pump for supplying blood under pressure was attached between the pre-filtration blood storage bag and the Y-tube connected to the digital pressure gauge.
[0039]
The shape of the volume constraining plate facing the outer surface of the blood inlet side and outlet side of the leukocyte removal filter is as follows. A 4 cm × 4 cm hole was formed in a 17 cm × 17 cm acrylic flat plate so as not to press around the blood inlet side and outlet side conduits. In addition, a groove having a width of 5 mm and a depth of 5 mm was provided along the conduit so that the blood inlet side and outlet side conduits were not bent by the volume restricting plate.
These two volume constraining plates were attached to a vise capable of adjusting the interval with compressed air so as to be parallel and facing each other, so that the interval between the volume constraining plates could be adjusted.
A leukocyte removal filter was placed between the two volume restraint plates loaded in the vise, and fixed so that the distance between the volume restraint plates was 15 mm (thickness of leukocyte removal filter + 5.5 mm). The leukocyte removal filter constrained by two volume constraining plates was horizontally disposed so that the blood inlet side was down and the blood outlet side was up, and the leukocyte-containing liquid was filtered.
[0040]
All prepared by adding ACD-A solution (composition: sodium citrate 22.0 g / L, citric acid 8.0 g / L, glucose 22.0 g / L) at a rate of 56 mL as an anticoagulant to 400 mL of bovine blood After 456 mL of blood was centrifuged, plasma and buffy coat were removed, and red blood cell preservation solution (composition: glucose 22.00 g / L, sodium chloride 9.00 g / L, adenine 0.27 g / L, mannitol 7.50 g / L) ) Was added to prepare a concentrated erythrocyte preparation (haematocrit is about 64%) and stored at 20 ° C. for 20 hours, and used as a leukocyte-containing solution.
[0041]
The leukocyte removal performance was evaluated by applying 721 g of concentrated erythrocyte preparation to the above leukocyte removal filter under pressure of 300 mmHg using a blood pump and filtering. Blood was continued to be supplied to the leukocyte removal filter using a blood pump until the concentrated red blood cell preparation in the pre-filtration blood reservoir bag was exhausted. The flow rate was 112 mL / min. Thereafter, the conduit between the leukocyte removal filter and the pre-filtration blood storage bag was blocked. Following this operation, at a moving speed of 10 mm / min, the distance between the two opposing volume restraint plates was reduced at a constant speed until reaching 9.5 mm (leukocyte removal filter thickness + 0 mm). The flow rate at this time was 78 mL / min. Thereafter, 30 mL of physiological saline as a rinsing solution was pressurized to 300 mmHg using a blood pump, poured into a leukocyte removal filter, and filtered blood was collected. Further, when the rinse liquid flowed out from the blood outlet side outlet pipe, the conduit was shut off and the recovery was completed. The flow rate at this time was 80 mL / min. The white blood cell concentration of the concentrated red blood cell preparation (hereinafter referred to as pre-filtration solution) before filtration and the collected concentrated red blood cell preparation (hereinafter referred to as recovery liquid) was determined, and thereby the leukocyte removal ability was determined.
[0042]
The pre-filtration leukocyte concentration was measured by diluting 10-fold with a Turku solution, injecting it into a Birkel-Turck hemocytometer, and counting the white blood cell count using an optical microscope.
Further, the leukocyte concentration in the collected liquid was measured by the following method. 1 mL of the recovered solution is diluted 10 times with a leuco plate solution (manufactured by SOBIODA). The diluted solution was mixed well and left at room temperature for 6 to 10 minutes. This was centrifuged at 2,750 g for 7 minutes, the supernatant was removed, and the liquid volume was adjusted to 1.02 g. The sample solution was mixed well, then injected into a nadget type hemocytometer, and the white blood cell concentration was measured by counting the white blood cell count using an optical microscope.
[0043]
From the weight of the concentrated red blood cell preparation (the weight of the white blood cell-containing liquid) in the pre-filtration solution and the weight of the recovered solution after filtration, the red blood cell recovery rate was determined by the following formula (1).
Red blood cell recovery rate (%) = 100 × (weight of recovered solution × hematocrit value of recovered solution) / (weight of leukocyte-containing solution before filtration × hematocrit value of solution before filtration) (1)
[0044]
Filtration from the time when the concentrated erythrocyte preparation reaches the filter material on the inlet side of the leukocyte removal filter until just before changing the interval between the volume restricting plate arranged on the inlet side and the volume restricting plate arranged on the outlet side, volume Starting to change the interval of the restraint plates, the filtration 2 is performed until the interval reaches a desired interval, and further, the flow rate of the recovered liquid from the outlet side outlet pipe is changed from the start of the injection of the rinsing liquid into the leukocyte removal filter. Up to 50 mL / min was classified as filtration 3, and the filtration time and the weight of the collected liquid in each filtration segment were measured. The flow rate was calculated by multiplying the recovered liquid weight by 1.08 as the specific gravity of the concentrated erythrocyte preparation, and dividing this by the filtration time.
[0045]
[Example 2]
The same operation was performed using the same leukocyte removal filter as in Example 1 except that the interval between the two volume constraining plates was set to 35 mm (thickness of leukocyte removal filter + 25.5 mm) at the start of filtration 1. .
Leukocyte removal ability was further improved by setting the interval between the volume restraint plates in the filtration 1 to be 35 mm wider than that of Example 1.
[0046]
[Comparative Example 1]
The same operation was performed using the same leukocyte removal filter as in Example 1 except that the interval between the two volume restraining plates was set to 10.5 mm (thickness of leukocyte removal filter + 1.0 mm) at the start of filtration 1. went.
When the pre-filtration blood was poured into the leukocyte removal filter at the start of filtration 1, it was found that uneven flow was observed and blood did not flow uniformly throughout the leukocyte removal filter material. The residual leukocyte concentration in the collected liquid was 2.3 times that of Example 1. Moreover, the flow rate 1 in the filtration 1 was as small as 40 mL / min.
[0047]
[Comparative Example 2]
At the start of filtration, the interval between the two volume constraining plates is set to 35 mm (thickness of leukocyte removal filter + 25.5 mm), and at the time of recovery, the interval between the two volume constraining plates is set to 35 mm (thickness of leukocyte removal filter + 25. 5 mm), that is, when the rinse solution was poured into the leukocyte removal filter (filtration 3), blood was collected without changing the interval between the volume restraint plates. Except for this operation, the same operation was performed using the same leukocyte removal filter as in Example 1.
When the rinsing liquid was poured into the leukocyte removal filter in the filtration 3, it passed through the blood remaining in the leukocyte removal filter almost without mixing and was discharged from the outlet side outlet tube. There was much blood remaining inside the leukocyte removal filter, and the red blood cell recovery rate was as low as 81%.
[0048]
In Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the same concentrated erythrocyte preparation, that is, the pooled blood was divided and used for filtration, and the same concentrated erythrocyte preparation was used in Example 1. Example 2, Comparative Example 1 and Comparative Example 2 were evaluated as a set.
The white blood cell concentration of the pre-filtration solution was in the range of 5,000 to 10,000 cells / μL. The residual leukocyte concentration in the collected liquid was relatively evaluated based on the results of Example 1, and the leukocyte removal ability was compared. The results are shown in Table 1 together with the flow rate and red blood cell recovery rate.
[0049]
[Table 1]
Next, an example and a comparative example in which filtration was performed while changing the volume restraining jig interval in the filtration 3 will be described.
[Example 3]
At the start of filtration, the interval between the two volume constraining plates is set to 35 mm (thickness of leukocyte removal filter + 25.5 mm), and the interval between the two volume constraining plates is 7.5 mm (thickness of the leukocyte removal filter). The same operation was performed using the same leukocyte removal filter as in Example 1 except that it was set to -2.0 mm).
[0051]
[Example 4]
At the start of filtration, the interval between the two volume constraining plates is set to 35 mm (thickness of the leukocyte removal filter + 25.5 mm), and the interval between the two volume constraining plates is 12.5 mm (thickness of the leukocyte removal filter) The same operation was performed using the same leukocyte removal filter as in Example 1 except that the setting was set to +3.0 mm.
[0052]
[Comparative Example 3]
At the start of filtration, the interval between the two volume constraining plates is set to 35 mm (thickness of leukocyte removal filter + 25.5 mm), and the interval between the two volume constraining plates is 5.5 mm (thickness of the leukocyte removal filter). The same operation was carried out using the same leukocyte removal filter as in Example 1 except that it was set to -4.0 mm).
The distance between the volume restraint plates of the filtration 3 was set to 5.5 mm, that is, the filter thickness was compressed by 4 mm, so that the resistance increased, and the rinsing liquid did not flow through the leukocyte removal filter. Therefore, the flow rate 3 and the red blood cell recovery rate could not be calculated. Further, the residual leukocyte concentration in the collected liquid is higher than in Example 3, and it is considered that the leukocytes once captured leaked due to the extreme compression of the leukocyte removal filter.
[0053]
[Comparative Example 4]
At the start of filtration, the interval between the two volume constraining plates is set to 35 mm (thickness of the leukocyte removal filter + 25.5 mm), and the interval between the two volume constraining plates in the filtration 3 is 14.5 mm (of the leukocyte removal filter). The same operation was performed using the same leukocyte removal filter as in Example 1, except that the thickness was set to 5.0 mm.
When the rinsing liquid was poured into the leukocyte removal filter in the filtration 3, it passed through the blood remaining in the leukocyte removal filter with little mixing, and was discharged from the outlet side outlet tube. There was much blood remaining inside the leukocyte removal filter, and the red blood cell recovery rate was as low as 86%.
[0054]
In Example 3, Example 4, Comparative Example 3 and Comparative Example 4, the same concentrated erythrocyte preparation, that is, the pooled blood was divided and used for filtration, and the same concentrated erythrocyte preparation was used in Example 3. Example 4, Comparative Example 3 and Comparative Example 4 were evaluated as a set.
The white blood cell concentration of the pre-filtration solution was in the range of 5,000 to 10,000 cells / μL. The residual leukocyte concentration in the collected liquid was relatively evaluated based on the results of Example 3, and the leukocyte removal ability was compared. The results are shown in Table 2 together with the flow rate and red blood cell recovery rate.
[0055]
[Table 2]
Next, in the filtration 2, an example and a comparative example evaluated by changing the change speed of the volume restraining jig interval will be described.
[Example 5]
In filtration 1, the distance between the two volume restraining plates is set to 35 mm (thickness of the leukocyte removal filter + 25.5 mm), and in filtration 2, the distance between the two volume restraining plates is set at a speed of 5.0 mm / min. The same operation was performed using the same leukocyte removal filter as in Example 1, except that the thickness was reduced to 9.5 mm (leukocyte removal filter thickness + 0 mm).
[0057]
[Example 6]
In filtration 1, the distance between the two volume constraining plates is set to 35 mm (thickness of leukocyte removal filter + 25.5 mm), and in filtration 2 the distance between the two volume constraining plates is set to 9. The same operation was performed using the same leukocyte removal filter as in Example 1 except that the thickness was reduced to 5 mm (thickness of leukocyte removal filter + 0 mm).
[0058]
[Comparative Example 5]
In filtration 1, the distance between the two volume restraining plates is set to 35 mm (thickness of the leukocyte removal filter + 25.5 mm), and in filtration 2, the distance between the two volume restraining plates is set at a speed of 2.0 mm / min. The same operation was performed using the same leukocyte removal filter as in Example 1, except that the thickness was reduced to 9.5 mm (leukocyte removal filter thickness + 0 mm).
In the filtration 2, the speed of narrowing the space between the volume restraining jigs was slow, and the flow rate at this time was slow, so the flow rate 2 was as small as 22 mL / min.
[0059]
[Comparative Example 6]
In filtration 1, the distance between the two volume restraint plates is set to 35 mm (thickness of the leukocyte removal filter + 25.5 mm), and in filtration 2, the distance between the two volume restraint plates is set to 9. The same operation was performed using the same leukocyte removal filter as in Example 1 except that the thickness was reduced to 5 mm (thickness of leukocyte removal filter + 0 mm).
In filtration 2, the speed of narrowing the interval between the volume restraining jigs was fast, and at this time, the pressure applied to the leukocyte removal filter exceeded 500 mmHg, and extreme hemolysis was observed. In Examples and Comparative Examples other than Comparative Example 6, no change was observed in the hematocrit value of the recovered liquid. In Comparative Example 6, the hematocrit value of the blood before filtration was 64%, whereas the recovered liquid The hematocrit value was as low as 62%, and the red blood cell recovery rate was as low as 87%. Moreover, since the flow rate 2 became faster than 200 mL / min, it was considered that leukocytes once captured by the leukocyte removal filter material leaked. The residual leukocyte concentration in the collected solution was 1.7 times that of Example 5.
[0060]
Example 5, Example 6, Comparative Example 5 and Comparative Example 6 are the same concentrated erythrocyte preparation, that is, Example 5 using the same concentrated erythrocyte preparation by dividing the pooled blood and using it for filtration. Example 6, Comparative Example 5 and Comparative Example 6 were evaluated as a set.
The white blood cell concentration of the pre-filtration solution was in the range of 5,000 to 10,000 cells / μL. The residual leukocyte concentration in the collected liquid was relatively evaluated based on the results of Example 5, and the leukocyte removal ability was compared. The results are shown in Table 3 together with the flow rate and red blood cell recovery rate.
[0061]
[Table 3]
【The invention's effect】
As described above, according to the filtration method, the volume constraining plate, and the filtration device of the present invention, it was possible to simultaneously achieve 1) enhancing leukocyte removal ability and 2) collecting blood with high efficiency. .
Claims (10)
（１）入口側に配置される体積拘束板と出口側に配置される体積拘束板との間隔を［白血球除去フィルターの厚み＋５ｍｍ］〜［白血球除去フィルターの厚み＋３０ｍｍ］に設定して白血球含有液を白血球除去フィルターの入口から加圧して流し込む工程、
（２）体積拘束板の間隔を［白血球除去フィルターの厚み−３ｍｍ］〜［白血球除去フィルターの厚み＋３ｍｍ］まで変化させながら５０ｍｌ／分以上２００ｍｌ／分以下の流速で白血球含有液を濾過する工程、
（３）その後、体積拘束板の間隔を［白血球除去フィルターの厚み−３ｍｍ］〜［白血球除去フィルターの厚み＋３ｍｍ］に固定しリンス液を白血球除去フィルターに供給して白血球除去フィルターに残留する白血球が除去された液体を回収する工程、
からなることを特徴とする白血球含有液から白血球を除去するための濾過方法。A leukocyte removal filter comprising a flexible container having an inlet and an outlet, and a sheet-like leukocyte removal filter material arranged so that the inside of the container is separated from the inlet side and the outlet side, the inlet side and the outlet side of the flexible container restraining Shinano the thickness of the leukocyte removal filter by volume restriction plate arranged on the outside to obtain a leukocyte is removed a liquid by passing a et white blood cell-containing solution, the leukocyte-containing solution is performed before storage leukocyte removal liquid In the filtration method of
(1) A leukocyte-containing liquid in which the distance between the volume restricting plate arranged on the inlet side and the volume restricting plate arranged on the outlet side is set to [thickness of leukocyte removal filter + 5 mm] to [thickness of leukocyte removal filter + 30 mm]. Pressurizing and flowing from the inlet of the leukocyte removal filter,
(2) A step of filtering the leukocyte-containing liquid at a flow rate of 50 ml / min to 200 ml / min while changing the interval between the volume restraining plates from [leukocyte removal filter thickness-3 mm] to [leukocyte removal filter thickness + 3 mm],
(3) Thereafter, the leukocytes remaining spacing volume restriction plate the leukocyte-removing filter thickness -3 mm] ~ fixed rinsing liquid in the leukocyte-removing filter thickness + 3 mm] is supplied to the leukocyte removal filter leukocyte removal filter Recovering the removed liquid;
A filtration method for removing leukocytes from a leukocyte-containing liquid, comprising:
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