MXPA97005411A - Procedure for ultrasound dosage of troponin i cardi - Google Patents

Abstract

The present invention relates to an ultrasensitive dosing procedure of cardiac troponin I, carried out by chemoluminescence.

Description

PROCEDURE FOR ULTRASOUND DOSAGE OF TROPONIN? I CARDIAC Field of the Invention The present invention relates to an ultrasensitive dosing method of cardiac troponin I, carried out by chemiluminescence.

Background of the Invention Cardiac infarction (MDI) always represents a medical emergency and remains the leading cause of mortality and cardiovascular morbidity in the world. In all cases, the treatment established aims to protect the cardiac tissue from irreversible necrosis. New therapeutic means, such as thrombolytics or first-order angioplasty, now allow the coronary circulation to be quickly restored, so that the size of the infarcted area is limited and the incidence of mortality and morbidity is reduced. These therapeutic tools are therefore more effective when they are put into practice Ref.025261 as soon as possible after the onset of clinical manifestations. Physicians who are faced with this pathology should be able to have diagnostic tools that work more and more. The dosage of the serum proteins and in particular of the enzymes has become a determining factor for the diagnosis of cardiac infarction and for the evaluation of the event in which a reperfusion fails. It is known that troponin is a myofibrillar protein complex, consisting of 3 proteins, troponins C, I and T. Cardiac troponin I is a contractile protein exclusively present in cardiac muscle [Wilkinson J.M. et al, Nature (1978), 271, p. 31-35; Wade R. et al, Genomics (1990), 7, p. 346-357], its physiological role is to inhibit, in the absence of calcium, the ATPase activity of the actin-myosin complex and thus prevent muscle contraction [Perry S.V., Biochem. Soc. Trans (1979), 7, p. 593-617]. At the time of the infarction due to the obstruction of one of the arteries that provide the nutrition of the heart (coronary artery), ischemia then a cardiac necrosis that results in destruction of cardiac cells and the release of cardiac troponin I in the blood. Cardiac troponin I thus represents a very specific marker of cardiac infarction. Thus, the dosage of troponin I for the early diagnosis of cardiac infarction [Am. Heart J. (1981), 110, p.1334-1344 Molecular Immunology (1992), 29 (2), p. 271-278]. Moreover, from now on it is an acquired eience that in certain patients the suffocation or unstable angina - which represents a critical stage of cardiac ischemia -, may be associated with a high risk of an uneted cardiac infarction or sudden death. Post-mortem studies on this category of patients have shown that the ap- "ication of these complications is very frequently preceded by cardiac micro-infarcts [Davies M.J. et al, Circulation (1985), 71, p. 699-708). The dosage of cardiac troponin I seems to be particularly interesting in the detection of subjects with this risk, in patients suffering from unstable suffocation, more especially for the diagnosis of microinfarcts. On the other hand, the dosage of troponin I can be considered at the time of surveillance of a thrombolytic therapy to confirm the success or failure of reperfusion, as well as in the immediate post-operative moment of interventions in cardiac surgery (coronary artery bypass, angioplasty, etc.). ). The dosage of troponin I thus finds its application in the diagnosis of cardiac graft rejections after transplantation and then of cardiotoxic therapeutic treatments using, for example, anthracyclines. The immunoenzymatic methods that allow the determination of troponin I are already known. Larue C. et al [Mol. Immunol. (1992), 29 (2), p. 271-278, Clin. Chem. (1993), 39/6, p. 972-979] disclose a sandwich-type in-enzyme dosing process that uses the chromogenic substrate of tetramethylbenzidine (TMB) -H202 for enzymatic revelation. After the revelation, the absorbance reading is made at 450 nm and the limit of detection, according to the authors, is 0.2 μg / 1. Another immunoenzymometric method of troponin I described by Bodor et al, allows the latter to be detected at concentrations of the order of 1.5 to 3.1 μg / 1 [Bodor et al, Clin. Chem. (1992), 38/11, p. 2203-2214; Adams J. et al., Circulation (1993), 88 (1), p. 101-106]. This dosage uses a chromogenic substrate of the alkaline phosphatase, p-nitrophenylphosphate, for the enzymatic detection, and the measurement is carried out at 405 nm. Thanks to these dosages, it is possible to demonstrate the presence of troponin I in the plasma of patients, approximately 4 hours after the onset of the clinical manifestations of cardiac infarction [Adams J. et al. Circulation (1993), 88 (1), p. 101-106]. However, the sensitivity of these immunoenzymometric dosages is much lower than that obtained by the dosages based on very sophisticated and difficult-to-operate methods, for example dosages based on the measurement of radioactivity [Am. Heart Journal, (June 1987), 113 (6), p. 1333-1334]. It is also known that the cyclic derivatives of the hydrazines, especially the diacylhydrazines, can be used as chemiluminescent reagents [Ros ell et al, Methods Enzymol. (1978), 5_7, p. 409-423]. The use of these reagents has been contemplated or carried out at the time of certain immunoenzymatic dosages [Thrope G.H.G. et al, Clin. Chem. (1985), 31, p. 1335-1341; Thrope G.H.G. et al, Medors. Enzymol. (1988), 133, p. 331-353] (Application WO 88/00695). On the other hand, detection methods for chemiluminescence are already known which put into operation the enzymatic decomposition of the 1,2-dioxetane derivatives. However, it is known that the putting into operation of these reagents requires intensive research since the expert in the art is confronted with multiple factors that limit the development of sensitive dosages (affinity of the different components of the dosage and especially of the system of antigens / antibodies, the enzyme marker, the substrate, the detection principle, etc.). In effect, an appropriate choice of the different reagents and conditions of the dosage is imposed. It is evident that it is not possible to imagine a sensitive and specific dosing 'when the noise or sound of the measurement (the background noise or the noise of the target or target) is important or when the signal / noise ratio is very small. Now, precisely this noise of the measurement depends on the different reagents and conditions of the chosen dosage. It has been frequently found that it is possible, using a certain type of anti-cardiac troponin I monoclonal antibodies and substrates suitable for enzymatic detection, to proceed to the chemilumungency dosing of troponin I with a very high sensitivity. Indeed, by applying the method of the invention, it is possible to obtain a sensitivity of the order of 2 to 5 ng / 1, which represents a sensitivity to approximately 1500 times greater than that of the most sensitive troponin I immunoenzymometric methods known up to now. . The present invention relates to a sandwich-type immunoenzymatic dosing method that allows the quantitative dosing of cardiac troponin I, characterized in that the substrates used for the enzymatic detection are chemiluminescent substrates, chosen from a large number of chemiluminescent substrates, in particular of the derivatives of a diazylhydrazine or 1,2-dioxetane. The object of the present invention is more precisely, an immunoenzymatic dosing process of the sandwich type, of cardiac troponin I: which activates or utilizes two monoclonal anti-cardiac troponin I antibodies, one of which is coupled with an anti-cardiac troponin I monoclonal antibody. enzyme marker, such antibodies have, either naturally, or by cooperativity, a high affinity towards cardiac troponin I, whose equilibrium dissociation constant is equal to or less than 10"8 M, preferably equal to or less than 10" 9 M. and which uses for the enzymatic disclosure a chemiluminescent substrate which is either a derivative of a diazylhydrazine, or a derivative of 1,2-dioxetane.

DETAILED DESCRIPTION OF THE INVENTION Indeed, the present invention relates to a quantitative immunoenzymatic dosing method of the sandwich type of cardiac troponin I, characterized in that the samples to be dosed or the standards are brought into contact with an anti-troponin monoclonal antibody I cardiac binding or coupled to an enzymatic marker and with another cardiac anti-troponin I monoclonal antibody, these monoclonal antibodies, either naturally, or by the cooperative effect, have for cardiac troponin I a dissociation constant at equal or lower equilibrium at 10 ~ 8 M, preferably equal to or less than 10 ~ 9 M, after which the enzymatic detection is carried out by the addition of a chosen chemiluminescent substrate and then the direct reading of the obtained light signal is carried out. The method of the invention can be carried out either by a manual system (diagnostic kit or dosing set) or by an automated system. According to the embodiment, it is possible to carry out either a dosage in a period of time, or a dosage in two periods of time. For dosing in a time interval, the samples to be dosed or the standards are contacted simultaneously with a monoclonal anti-cardiac troponin I antibody bound or coupled to an enzymatic label and with a second anti-troponin monoclonal antibody I cardiac is eventually fixed on a solid support. After incubation and washing, enzymatic revelation is carried out. The latter is carried out according to the invention by the addition of a chemiluminescent substrate derived from a diacylhydrazine or from 1,2-dioxetane. The amount of cardiac troponin I present in the samples to be dosed or in the standards is evaluated by direct reading of the light signal obtained. For the dosing in two time intervals, the samples to be dosed or the standards are contacted, either first with a monoclonal anti-cardiac troponin I antibody bound or bound to an enzymatic marker, then after the incubation, with a second cardiac anti-troponin monoclonal antibody I, optionally fixed on a solid support and then incubated again, or, finally, with a monoclonal anti-cardiac troponin I antibody bound or optionally fixed on a solid support , then after incubation and an eventual wash, with a second monoclonal anti-cardiac troponin I antibody bound or bound to an enzymatic marker and then incubated again. In the second case, it is possible to proceed immediately to a wash, then to the enzymatic detection which is carried out according to the invention, by the addition of a chemiluminescent substrate derived from a diacylhydrazine or from 1,2-dioxetane. The amount of cardiac troponin I present in the samples to be dosed or in the standards is evaluated by direct reading of the light signal obtained. For dosing in two time intervals, preferably, the samples to be dosed and the standards are first contacted with a monoclonal anti-cardiac troponin I antibody, bound or coupled to an enzyme label next to the antibody. incubation, with a second monoclonal anti-cardiac troponin I antibody fixed on a solid support and then incubated again. As monoclonal antibodies to cardiac anti-troponin I, all monoclonal antibodies that have a high affinity for cardiac troponin I and whose equilibrium dissociation constant is equal to or less than 10 ~ 8 M, preferably the same, can be used. or below 10 ~ 9 M. Any pair of monoclonal antibodies that have a bond or cooperative union can also be used against cardiac troponin I, this cooperativity results in an increase in the affinity of one of the two monoclonal antibodies towards the cardiac troponin I (equilibrium dissociation constant <; 10 ~ 8 M) when cardiac troponin I is left bound with the second antibody. Preferably, as the monoclonal anti-cardiac troponin I antibodies, the monoclonal antibodies 11E12 and 8E1 of the mouse described in Clin. Chem. (1993), 3_9, p. 972-979. Indeed, it has surprisingly been found that monoclonal antibodies 11E12 block the release of cardiac troponin I bound to antibodies 8E1. This phenomenon has been evidenced using the BIACORER system of PHARMACIA, and measuring the kinetic constants of association and dissociation of cardiac troponin I (cTnl) on monoclonal antibodies 8E1, in the presence or in the absence of antibodies. Results are provided in Table I.

TABLE I AcM 8El: cTnl AcM 8E1: cTnl + HE12 only CONSTANT KINETICS OF 3.2.10"2.8.10 -4 DISSOCIATION koff (S'1) CONSTANT KINETICS OF 5.8.105 4.5.10" ASSOCIATION ^ ON (M_1xS_1) CONSTANT OF DISSOCIATION 5.7.10"0.6.10" 9 IN EQUILIBRIUM Koff / kon (M) The results in Table I show that for 8E1 antibodies, the affinity is 10 times higher if cardiac troponin I is in the presence of monoclonal antibodies 11E12. More precisely, the dissociation constant at equilibrium is 10 times smaller (the kinetic constant of association does not vary). There is thus a cooperativity of the binding or binding of two cardiac anti-troponin I monoclonal antibodies to cardiac troponin I. Thanks to this effect of "blocking" the dissociation of the complex, it is possible to carry out the immunoenzymatic dosing process, object of the present invention, with this binding or coupling of the monoclonal antibodies. For the formation of the conjugate of the anti-cardiac troponin I-notional antibodies-enzyme marker, it is used as an enzymatic marker either alkaline phosphatase or peroxidase. Alkaline phosphatase is used when the chemiluminescent substrate is a 1,2-dioxetane derivative and the peroxidase when the chemiluminescent substrate is a derivative of a diacyl hydrazine. The monoclonal antibodies 8E1 or 11E12 can be used in particular to prepare the conjugates with an enzymatic label. Preferably, conjugates of monoclonal antibodies 11E12 with peroxidase and conjugates of monoclonal antibodies 8E1 with alkaline phosphatase are prepared. According to the embodiment, some solid support can be contemplated either of the polystyrene tubes on which the cardiac troponin I antibodies are fixed (in the case of the diagnostic kit or set), or of magnetic particles (especially ferric ones). ) or not, on which the anti-cardiac troponin I monoclonal antibodies are fixed (automated dosing). Conjugates of anti-troponin I monoclonal antibodies - enzyme label are prepared according to known methods [J. Histochem Cytochem (1974), 22. p. 1084-1091], The preparation of anti-troponin I monoclonal antibodies, fixed for example by covalent bonds on a solid phase, is also carried out according to the methods described in the literature [J. Immunological Methods, (1979), 31_, p. 231-236]. Due to the contacting of the samples to be dosed or of the standards with a monoclonal anti-cardiac troponin I antibody and / or a monoclonal anti-cardiac troponin I antibody bound or coupled to an enzymatic marker, the pH of the medium of reaction should preferably be slightly acidic. The pH must especially be between 5 and 6, more precisely between 5.4 and 5.7. To adjust the pH, different suitable buffer solutions or solutions of weak organic acids can be used, for example solutions or succinic acid buffers having a pH of 5.2 to 5.4. The incubation between the plasma or serum and the anti-troponin I antibodies or the standards is carried out between 20 ° C and 37 ° C and the incubation time can vary between 5 and 20 minutes. After the incubation, one or several washes are carried out, which are carried out at a temperature of 2 ° C to 37 ° C, preferably at a temperature below 10 ° C. For the washings, a phosphate buffer solution of pH 6.8 or a buffer solution tris of pH 8 is preferably used. As indicated above, either a diacylhydrazine derivative, more especially luminol, is used as the luminescent substrate [5]. -amino-2, 3-dihydroftalazin-l, 4-dione], or a 1,2-dioxetane derivative, more especially the lumin PPD [disodium salt of 4-methoxy 4- (3-phosphatephenyl) spiro (1,2 -dioxetan 3-adamantane-2 ')]. Luminescent substrates containing luminol are commercially available as for example the luminol-ECL immunoassay signal reagent RPN 190 marketed by Amersham or the chemiluminescent ELISA reagent BM from luminol 1582950 marketed by Boehringer Mannheim. Substrates containing a mixture of luminol and 4-iodophenol are preferred. Luminescent substrates containing lumgen PPD are also available commercially as, for example, the Lumi-Phos 530 marketed by Analytical Luminescence Laboratory. This reagent contains the lumigen PPD and a chemiluminescence promoter which is a surfactant derived from fluorescein. The enzymatic revelation is also carried out at a temperature between 20 ° C and 37 ° C. The reading of chemiluminescence is preferably carried out after approximately 2-10 minutes. To obtain the range of contrast of a quantitative dosage, standard (standard) solutions of purified human cardiac troponin I are used [Larue C. et al, Clin. Chem. (1993), 3_9, p. 972-979]. The invention also relates to the use of luminol and luminal PPD as chemiluminescent substrates for immunoenzymatic dosing of the cardiac troponin I sandwich type using or activating two cardiac anti-troponin I monoclonal antibodies, one bound or coupled with a enzymatic marker, in particular peroxidase, if the substrate is luminol, and alkaline phosphatase, if the substrate is the PPD lumigen, such antibodies (either naturally, or by cooperativity) have for cardiac troponin I a dissociation constant in the balance equal to or less than 10 ~ 8 M. The invention also relates to a cardiac troponin I dosing kit or package, comprising two cardiac anti-troponin I monoclonal antibodies, one bound or coupled to an enzyme label for such antibodies, which naturally, or by cooperativity, have a constant cardiac troponin I e of dissociation at equilibrium equal to or less than 10"9, and a chemiluminescent substrate derived from a diacylhydrazine, preferably luminol or a derivative of 1,2-dioxetane, preferably the luminal PPD. The following examples, given by way of nonlimiting, illustrate the invention.

EXAMPLE I Dosage of cardiac troponin I with an automated system The automated system used for immunoenzymatic dosing is the AccessR immunoassay system, a system marketed by Sanofi Diagnostics Pasteur. The dosage is carried out in the following manner: 50 μl of the sample to be dosed, 25 μl of a solution of mouse immunoglobulins at 4 mg / ml, 10 μl of a solution are introduced into the dose container or dome. of 0.1 M succinic acid, 50 μl of the conjugate of the monoclonal anti-cardiac troponin I antibodies of the mouse 8-Alkaline phosphatase (C = 5 μg / ml). After incubation for 5 minutes at 37 ° C, 50 μl ferric latex beads (Rhone Poulenc ref.MIR-070/60) are introduced on which the anti-cardiac troponin I monoclonal antibodies of the 11E12 mouse are covalently bound. The mixture is incubated for 36 seconds at 37 ° C, then the ferric latex balls are separated with the help of a magnetic field. The washing is carried out with the aid of a Tris buffer solution of pH 8, adding 200 μl of the substrate Lumi-PhosR 530. The revelation is carried out at 37 ° C and the luminescence generated by the reaction with a luminometer is measured. The total analysis time is 15 minutes. For the range or range of contrast solutions of purified human cardiac troponin I are used. A range or range of contrast corresponding to the concentrations between 0 and 50 μg / 1 is carried out. The sensitivity of the procedure, evaluated by the contrast curve, is 3.5 ng / 1.

EXAMPLE II Dosage of cardiac troponin I with a set or immunoenzymatic set In polystyrene tubes coated with monoclonal anti-cardiac troponin I antibodies from mouse 8E1, 150 μl of a succinate buffer solution containing 0.2% Tween 20, non-specific mouse immunoglobulins and 0.1% Kathon, 50 μl of the conjugate of monoclonal anti-troponin I cardiac antibodies of the mouse 11E12-peroxidase, and 200 μl of the sample to be dosed or of a contrast solution used for the range or interval of the contrast. For the contrast range, human serum containing 0 to 2 μg / 1 of purified human cardiac troponin I is used. It is incubated 15 minutes precisely under horizontal agitation at room temperature, then proceeds to wash the tubes as follows: the contents of the tubes are inverted or emptied into a container and the tubes are rinsed on an absorbent paper, - Wash by adding 1 ml of 0.1 M phosphate buffer, pH 6.8 containing 0.1% Tween 20 and 0.3% Kathon, maintaining the temperature above 8 ° C. This stage is repeated 3 times. After washing and removing any trace of the solution used for the latter, the enzymatic revelation is carried out using 300 μl of a mixture consisting of 100 parts of luminol (chemiluminescent ELISA reagent BM from Boehringer Mannheim) and 1 part of water oxygenated. It is left at room temperature and the luminescence is measured with a luminometer after 3 minutes. Each tube is read for exactly 30 seconds or exactly 10 seconds. The sensitivity of this dosage is 3 ng / 1. The values of the clear signal / noise ratio of the measurement (S-B) / B obtained according to the procedure described hereinafter and according to the procedure described by Larue C. et al [Mol. Immunol. (1992), 29 (2), p. 271-278; Clin. Chem. (1993), 39/6 p. 972-979] are provided in Table II hereinafter.

TABLE II Concentration of Procedure of the Procedure described Troponin I Example to by Larue et al Cardiac 100 ng / 1 S-B = 1200-95: 95 = 11.6 S-B = 150-50 = 2.0 95 50 ng / 1 S-B = 250-95 = 1.6 S-B = 0 (S = B) 95 B The values of the signal / noise ratios of the measurement, obtained by applying the method of the invention, prove its great sensitivity and its specificity.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (16)

1. An enzymatic dosing procedure of the sandwich type of cardiac troponin I, characterized in that two cardiac anti-troponin I monoclonal antibodies, one of which is bound or coupled to an enzymatic marker, are used or are operated, such antibodies, and either naturally or cooperatively, they have a dissociation constant at equilibrium equal to or less than 10"8 M, preferably equal to or less than 10" 9 M, and because a chemiluminescent substrate is used for the enzymatic detection of cardiac troponin I. derived from a diacylhydrazine or 1,2-dioxetane.

2. The method according to claim 1, characterized in that it comprises the following steps: a- the samples are contacted with an anti-cardiac troponin I monoclonal antibody bound or coupled to an enzymatic marker and with a second anti-troponin monoclonal antibody I cardiac, b- the enzymatic revelation is effected by the addition of a chemiluminescent substrate derived from a diacylhydrazine or 1,2-dioxetane, c- the amount of cardiac troponin I is evaluated by direct reading of the light signal obtained.

3. The method according to claim 1 or 2, characterized in that it comprises the following steps: a- the samples to be dosed or the standards are brought into contact simultaneously with a monoclonal anti-cardiac troponin I antibody bound or coupled to a marker enzymatic and with a second monoclonal anti-cardiac troponin I antibody optionally fixed to a solid support, b- the reaction mixture is incubated, c- then washed, d- the enzymatic disclosure is effected by the addition of a chemiluminescent substrate, derived of a diacylhydrazine or 1,2-dioxetane derivative, e- the amount of cardiac troponin I present in the samples that are dispensed or dosed or the standards, is evaluated by direct reading of the light signal obtained.

4. The method according to claim 1 or 2, characterized in that it comprises the following steps: a- the samples to be dosed or the standards are put in contact, either first with a monoclonal anti-cardiac troponin I antibody bound or coupled to an enzyme label, then after incubation, with a second cardiac anti-troponin monoclonal antibody optionally fixed on a solid support, and incubated again, or, firstly with an anti-troponin monoclonal antibody I cardiac eventually fixed on a solid support, then after incubation and optional washing, with a second monoclonal anti-cardiac troponin I antibody bound or coupled to an enzyme label and incubated again, b- the reaction mixture is washed immediately optionally, c- the enzymatic revelation is effected by the addition of a chemiluminescent substrate derived from a diacylhydrazine or derivative of 1,2 -dioxetane, d- the amount of cardiac troponin I present in the samples to be dosed or in the stan- dards is evaluated by direct reading of the light signal obtained.

5. The method according to any of claims 1 to 4, characterized in that the chemiluminescent substrate is luminol.

6. The method according to any of claims 1 to 4, characterized in that the chemiluminescent substrate is the luminal PPD.

7. The method according to any of claims 1 to 4, characterized in that the anti-troponin I monoclonal antibodies are the monoclonal antibodies having the characteristics of the mouse monoclonal antibodies 11E12 and 8E1.

8. The method according to any of claims 1 to 4, characterized in that the enzyme label bound or coupled to the anti-troponin I monoclonal antibodies is alkaline phosphatase or peroxidase.

9. The method according to any of claims 1 to 3, characterized in that the cardiac troponin I monoclonal antibodies bound or coupled to an enzyme label, are a conjugate of monoclonal antibodies against cardiac troponin I-peroxidase, said antibodies have the characteristics of the 11E12 mouse monoclonal antibodies and the chemiluminescent substrate is a derivative of a diacylhydrazine.

10. A method according to any one of claims 1, 2 or 4, characterized in that the cardiac troponin I monoclonal antibodies bound or coupled to an enzymatic label are a conjugate of monoclonal antibodies against cardiac troponin I-alkaline phosphatase, said antibodies have the characteristics of mouse monoclonal antibodies 8E1, and the chemiluminescent substrate is a derivative of 1,2-dioxetane.

11. The process according to any of claims 1 to 5, characterized in that the chemiluminescent substrate is a mixture of luminol and 4-iodophenol.

12. The method according to any of claims 1 to 4, characterized in that the contacting of the samples to be dosed or of the standards, with a monoclonal antibody anti-cardiac troponin I attached or coupled to an enzymatic marker and eventually to a second anti-troponin I antibody, is carried out at a slightly acidic pH comprised between 5 and 6, preferably between 5.4 and 5.7.

13. The process according to any of claims 1 to 4, characterized in that the washing solutions used before the disclosure have a pH equal to 6.8-8 and a temperature of 2 ° to 37 ° C, preferably at a temperature lower than 10 ° C.

14. The use of luminol as a chemiluminescent substrate for immunoenzymatic dosing of the cardiac troponin I sandwich type, which uses or activates two cardiac anti-troponin I monoclonal antibodies, one of which is bound or coupled with peroxidase, such antibodies either naturally or by cooperativity, they have for cardiac troponin I a dissociation constant in equilibrium equal to or less than 10"8 M.

15. The use of luminal PPD as a chemiluminescent substrate for the immunoenzymatic dosage of the sandwich type of cardiac troponin I, using or operating two monoclonal antibodies against cardiac troponin I, one of which is bound or coupled with alkaline phosphatase, such Antibodies either naturally or by cooperativity, have for cardiac troponin I a dissociation constant at equilibrium equal to or less than 10"8 M.

16. A cardiac troponin I dosing kit or package, characterized in that it comprises two cardiac anti-troponin I monoclonal antibodies, one of which is bound or coupled with an enzymatic label, such antibodies, either naturally, or by cooperativity, they have for cardiac troponin I a equilibrium dissociation constant equal to or less than 10 ~ 9 M, and a chemiluminescent substrate derived from a diacylhydrazine or 1,2-dioxetane.