title: An Fc gamma receptor I (CD64)-negative subpopulation of human peripheral blood monocytes is resistant to killing by antigen-activated CD4-positive cytotoxic T cells.
abstract: It has been demonstrated that in monocyte/T cell co-cultures activated with recall antigens, cytotoxic T cells were generated which are able to reduce the number of antigen-presenting monocytes. In previous studies we could show that a minor subset of monocytes, the Fc gamma receptor I-negative (CD64-) monocytes, exhibits significantly higher antigen-presenting capacity than the main population of monocytes (> 90%) which are Fc gamma receptor I-positive (CD64+). Therefore, we addressed the question whether they are also differentially susceptible to T cell-mediated killing. In the present study we demonstrate that the CD64- monocyte subset is more resistant to killing by antigen-activated T cells than CD64+ monocytes, as indicated by a higher viability and recovery of CD64- monocytes. This mechanism involves CD95 (Fas) antigen, since monocyte death in co-cultures with antigen-activated T cells could be partially reduced by blocking anti-Fas monoclonal antibodies (mAb). In agreement with this finding, although CD95 antigen was expressed on CD64+ and CD64- monocytes at comparable levels, killing of CD64- monocytes by activating anti-Fas mAb was lower than of CD64+ monocytes.
authors.affiliation: Forschungszentrum Borstel, Department of Immunology and Cell Biology, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Grage-Griebenow
authors.forename: J
authors.initials: J
authors.lastname: Baran
authors.forename: H
authors.initials: H
authors.lastname: Loppnow
authors.forename: M
authors.initials: M
authors.lastname: Los
authors.forename: M
authors.initials: M
authors.lastname: Ernst
authors.forename: H D
authors.initials: HD
authors.lastname: Flad
authors.forename: J
authors.initials: J
authors.lastname: Pryjma
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002469:Cell Separation; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic; D006801:Humans; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000276:immunology*; D009000:Monocytes / Q000276:immunology*; D017452:Receptors, IgG / Q000032:analysis*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014373:Tuberculin / Q000276:immunology; D019014:fas Receptor / Q000502:physiology
chemical_list: D017452:Receptors, IgG; D014373:Tuberculin; D019014:fas Receptor