Workshop conference report

Abstract

It was the aim of the workshop to summarize present knowledge of the variant creatine kinases in human blood. Discussion was centered on the nature, measurement, and clinical significance pfthese variants. On the basis of the presented results, the different creatine kinase variants can be classified äs follows: Normal size variants (80000 Daltons)These originale from postsynthetic modifications of the three dimeric isoenzymes creatine kinase-MM, MB or BB. The M subunit can be transformed by a serum constituent and these modifications result in at least three different creatine kinase-MM and two creatine kinase-MB variants, which still show catälytic activity.The mechanism of the postsynthetic alterations of creatine kinase-BB seems to be more complex: In vitro incubation of this isoenzyme even in a non-serum matrix changes its electrophoretic rnobility and decreases activity. In vivo there is evidence that on the one hand intact creatine kinase-BB molecules are directly removed from the circulation. On the other hand, however, inactive creatine kinase-BB-protein is reported to occur in serum. Variants with higher molecular weights (> 200 000 Daltons)These are termed macro creatine kinases.Macro creatine kinase type l comprises the immunoglobulin-bound creatine kinase isoenzyirfcs. Of these immune complexes, IgG-linked creatine kinäse-BB is well known and has been described in detail, whereas the occurrence of creatine kinase-MM-containing macro creatine kinases is still questionable. Macro creatine kinase type l is found in the blood of about 2% of all hospitalized patients. It occurs mainly in elderly women, but it is not known whether it has any special clinical significance.