Atypical Serum Creatine Kinase Isoenzyme Pattern Caused by Complexing of Creatine Kinase-BB

Summary: 12 cases are described, which show high serum creatine kinase-BB levels, as well as atypical creatine kinase activity band located between normally migrating creatine kinase-MM and creatine kinase-MB. It is shown that the altered properties of the serum creatine kinase-BB, namely its molecular size, heat resistance, electrophoretic mobility, but not its immunological behavior, are caused by complexing with kappa-chains of immunoglobulins G or A. The complex occurring in vivo could also be produced in vitro by using purified patients ' IgG and human creatine kinase-BB. The interaction of creatine kinase-BB with immunoglobulins possibly protects the enzyme against intravascular degradation in vivo, and may therefore account for the high creatine kinase-BB levels observed in these patients. Atypisches Isoenzymmuster von Kreatinkinase im Serum infolge Komplexbildung von Kreatinkinase-BB mit Immun· globulin G und