Immunohistologic demonstration of myocardial proteins with applications.

The authors used antibodies specific for creatine kinase MB isoenzyme (CK-MB) and myosin light chain-1 (MLC-1) for immunohistologic staining. At appropriate dilutions of antibody, frozen sections of human heart muscle were positive for both CK-MB and MLC-1, whereas sections of human skeletal muscle were negative for both proteins. Staining for both CK-MB and MLC-1 also was demonstrated in an immature teratoma. Furthermore, staining was localized to the rhabdomyosarcomatous elements within the teratoma; other components of the tumor did not stain for CK-MB or MLC-1. Biopsies of skeletal muscle revealed that regenerative, but not intact normal or degenerating, fibers also contained CK-MB and MLC-1. Immunohistologic stains for CK-MB and MLC-1 may be useful as tumor markers and as markers for regenerative muscle fibers.