Creatine Kinase Isozymes Other than the BB Type in Cerebrospinal Fluid and Changes in Their Levels Associated with Central Nervous System Diseases

The total actvity level and isozyme patterns of creatine kinase (CK) were measured for 154 pairs of cerbrospinal fluid (CSF) and the concurrent sera from 123 neurological patients, on the basis of the colorimetric method and agarose-gel electrophoresis, respectively. The results showed that the CSF isozymes other than the BB type, as well as the generally dominant BB isozyme, are consistently present in human CSF and that their levels are also increased under various pathological conditions. It was considered from the results of other examinations that elevation of the CSF CK minor isozyme levels occurred due to at least one of three possible causes；(a) overflowed entrance of the MM isozyme, which is absolutely dominant in the blood plasma, under its highly raised condition in muscular diseases and functional psychosis etc., (b) increased entry of the plasma proteins including CK-MM due to accelerated permiability of the blood-brain-CSF barrier membrane in inflammatory disorders of brain and/or meninges etc., and (c) release of the brain minor isozymes, such as CK-MB, -MM and brain mitochondrial CK, from the organic damaged tissues in which they were located. Among them, (c) which was rarely found in cerebral infarction, degenerative diseases in the central nervous system and cranial polyneuritis etc. is undoubtedly most significant from the viewpoint of biochemical diagnosis, since it occurs independently of the concurrent serum enzyme level and the total GSF protein content.