Expression of HLA-DR antigens on T lymphocytes

Our data have demonstrated, for the first time, expression of HLA-DR antigens on heated T cells (45 degrees C, 1 h) and have confirmed the occurrence of these antigens on mitogen-stimulated T cells. HLA-DR antigens were detected by microlymphocytotoxicity employing defined and non-defined anti-HLA-DR sera. The HLA-DR T cell antigens proved to be the same as the ones expressed on B cells from the same donor. In addition, extra reactions were observed on mitogen-stimulated and on heated T cells which could be abolished by absorption with cytotoxicity negative B cells of the same donor (cytotoxicity-negative-absorption-positive phenomenon).