Direct measurement of creatine kinase-MB activity in serum after excretion with a monoclonal antibody specific to the MB isoenzyme

Fusion of splenocytes from A/J mice immunized by creatine kinase (EC 2.7.3.2)-MB isoenzyme (CK-MB) with SP2/0-Ag14 myeloma cell line generated hybridomas producing monoclonal antibodies specific to CK-MB. One of these monoclonal antibodies ('Conan-MB') was used to develop a direct assay for CK-MB activity. In the assay, serum is incubated for 30 min at room temperature with 'Conan-MB' immobilized on latex beads. The beads are then washed, and CK-MB activity bound to the antibody is measured after incubation with CK enzyme reagent for 30 min at 37°C. Results with the assay correlated well (r = 0.997) with those for CK-MB concentration as measured by a two-site immunoassay. Neither CK-MM, CK-BB, mitochondrial CK, nor a hemolysate of erythrocytes interfered. Use of this unique monoclonal antibody allows rapid, precise, and direct determination of CK-MB activity.