Immunohistochemical studies on human myocardial mast cells.

Immunoreactivity of resting human heart mast cells [MCs] to a wide variety of antisera was studied in the right atrial auricles and papillary muscles of patients subjected to open heart surgery. All MCs reacted positively to antisera against leukocyte common antigen, vimentin and histamine. Some MCs positively reacted with antisera against lysozyme, alpha 1-antitrypsin, alpha 1-antichymotrypsin, and S-100 protein. Immunostaining pattern was similar in papillary muscle MCs and atrial MCs. There was no reaction with antisera against epithelial, tumor, neuronal, and endocrine cell antigens used in this study. Our studies displayed the existence of differences in immunoreactivity between human neoplastic and reactive MCs and heart resting mast cells. This may reflect the heterogeneity of human MCs from different anatomic sites and/or different pathological processes.