title: Differential MHC class II expression on human peripheral blood monocytes and dendritic cells.
abstract: Both monocytes (MO) and dendritic cells (DC) in human peripheral blood are of a plastic-adherent nature. The expression of the MHC class II sublocus products HLA-DP, -DQ and -DR on human peripheral blood transiently adherent cells (TA) was examined by an immunocytochemical staining technique. While most TA showed strong expression of molecules of the HLA-DR subtype, only a small proportion of cells (2-6%) showed strong HLA-DP or -DQ positivity. This strong expression of the HLA-DP and HLA-DQ sublocus products by a subset of TA was seen only after short-term culture; freshly isolated cells expressed comparatively low levels of these molecules. Enrichment for Fc receptor-negative or low-density cells from TA produced populations with strong HLA-DQ and -DP expression. Such co-enrichment of the strongly HLA-DQ+ and strongly HLA-DP+ cells suggests that the same cells express high levels of both types of MHC class II molecule. Immunocytochemical analysis of TA indicated that the strongly HLA-DQ+ cells, at least, were only weakly or non-reactive with the MO-specific monoclonal antibodies OKM1, UCHM1, MO2 and EB11. In addition, strongly HLA-DQ- or -DP-positive cells were poorly phagocytic in comparison with the majority of adherent cells. The apparent FcR-negative, low-density and weakly phagocytic nature of the strongly HLA-DQ/DP+ cells, combined with their lack of reactivity with several MO-specific antibodies, suggests that they may represent the DC component of TA. Such strong HLA-DQ/DP expression by DC may aid their positive identification in human peripheral blood and may be of relevance to DC function in antigen presentation.
authors.affiliation: Paterson Institute for Cancer Research, Christie Hospital and Holt Radium Institute, Manchester, U.K.
authors.forename: C F
authors.initials: CF
authors.lastname: Brooks
authors.forename: M
authors.initials: M
authors.lastname: Moore
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology; D002448:Cell Adhesion; D003713:Dendritic Cells / Q000276:immunology*; D006681:HLA-D Antigens / Q000276:immunology*; D006682:HLA-DP Antigens / Q000276:immunology; D006683:HLA-DQ Antigens / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D009000:Monocytes / Q000276:immunology*; D010587:Phagocytosis; D011961:Receptors, Fc / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D006681:HLA-D Antigens; D006682:HLA-DP Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D011961:Receptors, Fc