HLA‐D‐Associated Ia‐Like’ Antigens on Human Macrophages

Human macrophages procured by culture of adherent peripheral blood mononuclear cells were investigated for reactivity in complement-dependent cytotoxicity tests with antisera having specificity for HLA-D-associated 'Ia-like' B-cell antigens. The antisera were found to be cytotoxic for 30%-70% of the macrophages from donors whose B cells were also reactive, and absorption with B cells also removed macrophage cytotoxicity. A B-cell xenoantiserum was also cytotoxic to macrophages. It is concluded that the HLA-D-associated 'Ia-like' antigens present on B cells are also expressed by macrophages, at least on a subpopulation.