JPS62293163A - Immunological analysis - Google Patents

Abstract

PURPOSE:To enable the detection of antibody excess and antigen excess and to easily obtain correct values by changing the antigen quantity or antibody quantity in a reagent and making a 2nd measurement after a 1st measurement and comparing the results of the two measurements. CONSTITUTION:Two kinds of concns. C1, C2 in the case of the antibody excess and antigen excess are obtd. with the same measured value Va if the 1st measurement is first made in order to determine the antigen concn. in the sample by the measurement of absorbancy. The antigen quantity or antibody quantity in the sample or reagent is then changed and the 2nd measurement is made, by which the measured absorbancy value Va' is obtd. For example, the result of the comparison made between Va and Va' when a specified quantity of the antigen is added to the sample reveals that the absorbancy increases with an increase in the antigen concn. in the antibody excess region in the case of 1) Va<Va'. The results, therefore, indicates that the sample is in the antibody excess region and that the concn. C1 is consequently the correct concn. value. The absorbancy decreases with an increase in the antigen concn. in the case of 2) Va>Va', which indicates that the sample is in the antigen excess region and that the concn. C2 is consequently the correct concn. value.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to an immunoassay method for quantifying antigen (or antibody) IR in a sample.

(Prior Art) Clinical chemistry tests in hospitals and the like have been increasingly automated in recent years, and automation of not only biochemical tests but also serum tests has become popular. Furthermore, as clinical knowledge regarding various diseases is accumulated, substances that are said to be closely related to these diseases are being identified. These substances, which have recently been attracting attention, are generally present in serum at only minute amounts. These substances are analyzed and measured using antigen-antibody reactions. Among these, a method using a radioisotope as a label (RIA method) is suitable for measuring minute components. In addition, immunochemical measurement methods such as immunoturbidimetry, Utex turbidimetry, fluorescence labeling immunoassay, and elemental labeling immunoassay have recently come into use.

In the conventional measurement method, the relationship between antigen concentration and absorbance is determined in advance as shown in FIG.
I was trying to find the concentration C corresponding to .

(Problems to be Solved by the Invention) However, with the conventional method as described above, if the sample contains a high concentration of antibodies or antigens, the measured value of absorbance will be low, so the second As shown in the figure, the same measured value Va
Two types of concentration CI in case of excess antibody and excess antigen for
, C2, which caused erroneous measurements.

It is an object of the present invention to provide an immunoassay method that solves the problems of the conventional methods as described above and allows the detection of antibody excess and antigen excess to easily obtain correct values.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention changes the amount of antigen or antibody in the sample after performing the first measurement with a predetermined amount of sample or reagent. Alternatively, a second measurement was performed by changing the amount of antigen or antibody in the reagent, and the results of both measurements were compared to determine the amount of antigen or antibody in the sample.

(for production) Since the present invention has the above configuration, it operates as follows.

That is, when measuring the antigen concentration in a sample by measuring absorbance, for example, if the first measurement is performed in the same manner as before, as mentioned above, antibody excess and antigen excess will be detected for the same measurement value Va. Two concentrations C1 and C2 are obtained in the case of .

Then, when a second measurement is performed, for example by adding a certain amount of that antigen to the sample, a measured value of its absorbance is obtained (for convenience of explanation, this measured value will be referred to as Va').

Therefore, when comparing Va and Va', ■Va<Va
In the case of ', the absorbance increases as the antigen concentration increases in the antibody-excessive region, so if va<va', the sample is in the antibody-excessive region, and therefore the concentration C1 is the correct concentration value. It turns out that it is.

■On the contrary, if va >va', in the antigen-rich region,
Since the absorbance decreases as the antigen concentration increases, Va〉■a
’, the sample is in the antigen-rich region and the concentration C2
It can be seen that is the correct concentration value.

As a means of adding a certain amount of antigen to the sample in the second measurement, it is possible to add only the antigen to the same sample as in the first measurement, or to increase the sample ω itself in the second measurement. It is also possible.

Furthermore, the present invention is not limited to increasing the antigen in the sample during the second measurement;
．． Since it is possible to recognize whether the antigen is excessive or the antibody is excessive from the second measurement result, it is possible to measure the correct concentration value.

Note that when measuring the antibody concentration in a sample (in this case, the reagent contains an antigen), the antibody may be increased or decreased during the second measurement.

Each of the above methods was performed by changing the amount of antigen or antibody in the sample, but even if the amount of antigen or antibody in the reagent is changed, it is easy to obtain the correct concentration value due to the same effect. can be understood.

(Example) Hereinafter, a case will be described with reference to the drawings, taking as an example a case in which the amount of an antigen in a sample is measured by turbidimetry using latex particles to which an antibody against the antigen is bound as a reagent.

In the method of the present invention, as shown in FIG. 1, the antigen-absorbance relationship (curve A) is determined in advance as in the conventional method.

After that, if you want to add a certain amount of antigen to sample a and this sample a, you may add only the antigen, or you may increase the sample mother and increase the antigen as a result) Sample a
The measured values Va and Va' are calculated by 1q for two types of samples.

The amount of antigen to be added is determined appropriately depending on the type of antigen to be measured. For example, when measuring AFP (alpha fetoprotein), increase the sample amount by 30 μl to a = 50ti1, such as a' = 80 μl. do.

Alternatively, 20 ng/m for a 50μ sample as a′
Assume that 30 μm of AFP No. 1 is added.

Here, sample a is measured (for IaVa, the concentration is C1
, C2 can be taken, but when sample a has excess antibody, concentration C1 is the correct concentration value, and when sample a has excess antigen, concentration C2 is the correct concentration value.

Therefore, if it is known in which excess region sample a is located, the correct concentration value can be detected.

Therefore, in the method of the present invention, the absorbance Va of sample a and the absorbance a' of sample a' are compared and discriminated as follows.

(2) When va<va' In the antibody-excess region, as the antigen concentration increases, the absorbance also increases. In other words, it is a curve that slopes upward to the right.

Since sample a' contains an antigen, sample a' has a higher antigen concentration than sample a' (II degree C3).
The absorbance Va' is larger than Va in the antibody excess region.

Therefore, when Va<Va', the non-pure a is in the antibody excess region, and the concentration C1 is the correct concentration value.

■If Va>Va’ In the region of antigen excess, the absorbance decreases as the antigen concentration increases.

Therefore, for the same reason as mentioned above, sample a is in the antigen excess region when va>va', and the concentration C2 is the correct concentration value.

Furthermore, in this embodiment, by creating a curve B shown by a broken line in FIG. 1, it is possible to more easily determine the correct density value.

That is, in contrast to curve A showing the antigen concentration in sample a when sample a is measured, the antigen concentration curve in sample a when sample a' is measured is determined in advance as curve B in FIG. 1.

Therefore, if such a curve B is created, va>v
The concentration in the case of a' can be uniquely determined on the line connecting the intersection of Va' and curve B and the intersection of Va and A in the antibody excess region.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments, and can be modified as appropriate within the scope of the gist of the present invention.

For example, in the above example, the amount of antigen in the sample was changed, but the amount of antibody in the reagent may be changed.

These changes in the amount of antigen or antibody may be an increase or a decrease.

Further, in the above embodiment, the absorbances Va and Va' were compared, but it goes without saying that the correct JfU value can also be found from the comparison result by comparing the concentration values C1 and C3, for example.

[Effects of the Invention] As described in detail below, according to the present invention, when measuring the amount of antigen or antibody in a sample, it is possible to eliminate the cause of measurement error, and to easily obtain correct values. be able to.

4. Brief explanation of the drawings FIG. 1 is an explanatory diagram of the immunoassay method according to the present invention, and FIG. 2 is an explanatory diagram of the conventional method.

Claims (3)

[Claims] (1) In an immunoassay method that measures the amount of antigen or antibody in a sample using an antigen-antibody reaction between a sample and a reagent, performing a first immunoassay measurement using a predetermined sample and reagent, Perform a second immunoassay measurement by changing the amount of antigen or antibody in the sample, or by changing the amount of antibody or antigen in the reagent, and compare the results of both measurements to determine the amount of antigen or antibody in the sample. An immunoassay method characterized by determining. (2) The amount of antigen or antibody in the sample at the time of the second measurement is determined by whether a certain amount of antigen or antibody is added to the sample,
Alternatively, the immunoassay method according to claim 1, wherein the amount of the sample itself is increased to thereby increase the amount of antigen or antibody. (3) The amount of antigen or antibody in the reagent at the time of second measurement can be determined by adding a certain amount of antigen or antibody to the reagent, or by increasing the amount of reagent itself, resulting in an increase in the amount of antigen or antibody. An immunoassay method according to claim 1.