[The current aspect of serum creatine kinase in the laboratory medicine].

Two novel immunochemical methods for CK isozyme analysis using monoclonal antibodies were evaluated. One is an immunochemiluminescence method for CK-MB. The other is an immunochemical method for CK-MM isoform. 1) CK-MB: The conventional methods for CK-MB analysis currently used in many laboratories measure enzyme activity, but the immunochemiluminescence method, currently developed, has a completely different principle. By use of a specific monoclonal antibody for CK-MB, it can measure CK-MB as protein dose, including biologically inactive CK-MB. Therefore, we can avoid several error factors in the measurement of CK-MB. This immunochemiluminescence method enables us to observe the true CK-MB behavior in the blood stream. 2) CK-MM isoform: The measurement of fluorescence intensity after electrophoresis is a routine method for the analysis of CK-MM isoform (MM1, MM2, and MM3). Recently a monoclonal antibody against the M-subunit of CK-MM isoform has been developed. This antibody can recognize and inhibit the M-subunit, containing a lysine residue at the C-terminal end. Therefore, the application of the monoclonal antibody enables us to measure quantitatively CK-MM isoform without electrophoresis. 3) CK-MM isoform converting factor: CK-MM3 is converted to MM1 via MM2 in the blood stream. The nature of this converting factor is suspected to be a carboxypeptidase-N, but this has not been confirmed.

A new immuno quantitative method by latex agglutination--application for the determination of serum C-reactive protein (CRP) and its clinical significance.

We developed a new method for the determination of CRP by latex immunoassay which measures the increase in optical density as a result of latex agglutination due to antigen-antibody reaction. This latex agglutination photometric immunoassay can be used for quantitative analysis of various biological substances. We have established the best conditions for CRP determination for the instrument employed here (LA system) which allows rapid and accurate to low concentration measurement. The measurement range of the system is from 0.01-3 mg/l (non-diluted method), which when compared to the lower detection limit of RIA, 3 micrograms/l, it has the same order of magnitude. It is more sensitive than radial immunodiffusion which has the lower detection limit of 2 mg/l and has the similar value to that of radio-electroimmunodiffusion, 10 micrograms/l. Furthermore, the usual method used in the clinical laboratories, the capillary microprecipitation method, has the lower detection limit of approximately 10 mg/l. The method presented here is adequately sensitive to measure the low concentration of CRP among healthy individuals which has not been possible except by using RIA. The normal value derived from 106 healthy individuals by this method is found to be 0.2 +/- 0.2 mg/l (mean +/- 2SD).