Three atypical serum creatine kinases in a patient with carcinoma of the colon

Three electrophoretically atypical creatine kinase (CK) bands were found simultaneously in the serum of a patient with terminal carcinoma of the colon. The atypical CKs were found at the cathodal side of CK-MB (CK-X1), at a sample application point (CK-X2), and at the anodal side of CK-MM (CK-X3) on agar plates. Our data seemed to suggest that CK-X1 was predominantly a CK-IgA/beta-lipoprotein complex, CK-X3 was a CK-IgG complex, and CK-X2 was macromolecular, different from both CK-X1 and CK-X3. The light chains of IgA and IgG were both of the lambda type. All native isoenzymes comprising these atypical CKs were identified as MM type. There was no change of the electrophoretic pattern of serum CK isoenzymes throughout the course of the study.