title: HLA-DR antigens on lymphoid cells differ from those on myeloid cells.
abstract: The human HLA-D region-related loci encode antigens which are structurally homologous and functionally analogous to the murine Ia molecules in mice. In addition to a role in immune regulation, it has been shown that the human D region-associated molecules are expressed on immature haematopoietic precursors and may also be involved in the regulation of haematopoiesis. Here we present evidence that distinct 'Ia-like' antigens are found on different haematopoietic cells. Approximately half of the Ia-like molecules expressed by B cells and activated T cells have an 'epitope' which is unique to lymphocytes and is not detectable on the Ia-like molecules of haematopoietic precursors or monocytes. This kind of lineage-restricted variation in Ia expression is a potential basis for selective compartmentalization and regulation of DR-associated function.
mesh_terms: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000276:immunology; D000939:Epitopes; D005434:Flow Cytometry; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology*; D009000:Monocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II