Atypical Serum Creatine Kinase Isoenzyme Pattern Caused by Complexing of Creatine Kinase-BB with Immunoglobulins G and A

Abstract

Twelve cases are described which show high serum creatine kinase-BB levels and atypical creatine kinase activity band located between normally migrating creatine kinase-MM and creatine kinase-MB. 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 [Ig] G or A. The complex occurring in vivo could also be produced in vitro by using purified patients'' IgG and human creatine kinase-BB. Interaction of creatine kinase-BB with Ig possibly protects the enzyme against intravascular degradation in vivo, and may account for the high creatine kinase-BB levels observed in these patients.