Radioimmunoassay for subunit B in isoenzymes CK-MB and CK-BB of creatine phosphokinase.

We report the development of a double-antibody system for radioimmunoassay of CK-B subunit in isoenzymes CK-MB and CK-BB of creatine phosphokinase. With our method, 4.1 ng/ml of isoenzyme CK-BB can be detected. Within-run and between-run coefficients of variation are respectively 5.3% and 19.6% Analytical recovery of added antigen is 98.9 +/- 14.7%. The CK-B concentration in sera from 20 healthy adults was less than 75 ng/ml. In sera from 25 patients with a rise in CK-total activity, but without CK-MB or CK-BB activity tested with the previous reported immunological methods, we found CK-B concentrations in the range 0--86 ng/ml. In contrast, in 23 sera from patients with acute myocardial infarction within the last 48 hours CK-B concentration was in the range 104--225 ng/ml.