Immunohistochemical distribution of heart-type fatty acid-binding protein immunoreactivity in normal human tissues and in acute myocardial infarct.

The cellular distribution of heart-type fatty acid-binding protein (H-FABP) immunoreactivity was examined in normal human tissues using a polyclonal antibody against human H-FABP. Immunoreactivity was detected in cardiomyocytes of both ventricles and atria as well as in all striated muscles investigated. In addition, staining was frequently observed in parietal cells of the stomach, renal epithelial cells, acinar and ductal cells of the breast, ductal cells of the salivary gland, corpus luteum, and Leydig cells of the testis. Adipocytes and vascular endothelial cells were positive but other tissues and cells examined were negative. Old infarcts of the heart replaced by fibrous connective tissues were not labelled. Necrotic cardiomyocytes and morphologically normal cardiomyocytes in acute ischaemic lesions 1 h after onset showed reduced or no H-FABP immunoreactivity. Thus, decreased immunoreactivity for H-FABP may be a good histological marker of damaged cardiomyocytes.