Immunochemical assay for creatine kinase-MB isoenzyme

Claim 1

A process for quantitatively determining in a biological fluid sample the presence of creatine kinase-MB isoenzyme where the creatine kinase can occur in biological fluids in a plurality of isoenzyme forms containing the subunit M or B or both, the process comprising: a. incubating in a first reaction vessel a first of two portions of the biological fluid sample with a first antibody which selectively binds immunologically with the creatine kinase isoenzymes containing the M subunit by selective immunoinhibition of the M subunit in the first portion of the sample and thereafter quantitatively measuring the B isoenzyme activity of the first portion of the sample, b. incubating in a separate reaction vessel the second of two portions of the biological fluid sample with: (i) an antibody which selectively binds immunologically with the creatine kinase isoenzymes containing the M subunit in the second portion sample; and (ii) a second antibody which selectively binds immunologically to form a solid phase with the antibody binding the creatine kinase isoenzymes containing the M subunit, to produce as a precipitate the reaction product of said second antibody with said other antibody and said creatine kinase isoenzymes containing the M subunit and thereafter quantitatively measuring the B isoenzyme activity of the supernatant in said second portion; and c. determining the CK-MB activity in said sample from said measurements through the substraction of the measurement obtained in the second portion, from the measurement obtained in the first portion.