Multiple Occurrence of Macro Creatine Kinase in One Family

isoenzyme activity and mass concentration, and distribu-tion of CK isoenzymes (by electrophoresis) in serum from five members of one family. The mother and two young children showed CK-lgG complexes in their sera. The concentration of the CK-lgG complexes in the children decreased over time, suggesting that the complex in-volved maternal lgG and had been transferred across the placenta from the mother to her children. Additional Keyphrases: enzyme-Immunoglobulin complexes catalytic.u lmmunoreactivityof enzymes Macro creatine kinase (macro CK), “atypical CK, ” is a rare, but not unheard-of condition seen predominantly in elderly persons. One characteristic of this condition is the presence of CK isoenzyme MB (CK-MB) at a rela-tively high concentration, which is sometimes greater than the normal total activity of the enzyme (1-3). Such a combination could be confusing because the enzyme pattern mimics that of a myocardial infarction. One reason for this condition is the occurrence of a CK-IgG I complex in the serum of affected persons (4, 5). This ixnmunocomplex can be detected by a conventional im-munoinhibition test for CK-MB or by electrophoresis for CK isoenzymes, but not by measuring the mass concen-tration of CK-MB. No disease has yet been identified in connection with the occurrence of this enzyme-IgG complex. The condition is usually detected by chance, when CK-MB measurement is performed by immuno-inhibition test. The enzyme-antibody complex can per-sist for several years, indicating either that its half-life is very long or that there is a constant reforming of the complex. Here we describe our observation of CK-IgG com-plexes in three members of one family: a mother and two of her three children, each child at an age of approxi-mately 2 months