HLA antigen expression and induction by γ-interferon in cultured human trophoblasts

The expression and regulation of HLA antigens were examined in isolated human trophoblasts. Immunocytochemical studies that used monoclonal antibodies against class I (HLA-A, B, and C) antigens revealed that both cytotrophoblasts and syncytiotrophoblasts can express HLA heavy chains and β 2 -microglobulin. Expression of these antigens increased with time in culture. The addition of recombinant γ-interferon (1000 U/ml) to the cultures significantly increased cellular staining for these antigens over controls throughout the 72-hour time course studied. In addition, we noted that gene expression for HLA class I heavy chain was also markedly augmented by the addition of γ-interferon. Expression of class II (HLA-DR) antigens was not detected in any of the experiments. These results suggest that during in vitro differentiation, cytotrophoblasts can express class I HLA antigens and the genes controlling their production can be regulated. Alterations in the expression or suppression of these antigens during pregnancy could be responsible for some pregnancy complications.