EXPRESSION OF PORCINE MAJOR HISTOCOMPATIBILITY ANTIGENS IN CARDIAC TISSUE

In this study we have used monoclonal antibodies directed against anti gens of the major histocompatibility complex (MHC) class I and class I I to reveal the detailed cellular distribution of swine lymphocyte all oantigens (SLA) in cardiac tissue. By applying a sensitive immunophosp hatase staining reaction we detected the ubiquitous expression of SLA class I and class II on the vascular endothelium. Endothelial cells of capillaries and blood vessels were intensely stained structures in th e examined swine hearts. Similar staining patterns were observed in co ntrol experiments with anti-von Willebrand factor serum and Dolichus b iflorus lectin used as immunohistochemical markers for endothelial cel ls. The luminal layer of studied pulmonary valves exhibited a strong s taining reaction with anti-SLA class I and class II antibodies. In con trast, normal cardiac myocytes failed to express immunodetectable amou nts of either of the SLA determinants. Intercalated discs in porcine h eart tissue did not react with either anti-SLA class I or class II ant ibodies. Our data showing the abundant expression of SLA molecules on endothelial cells in normal swine heart may have physiological implica tions in cell-mediated rejection occurring in xenotransplanted hearts.