title: Characterization of accessory cells required for helper T cell induction in vitro: evidence for a phagocytic, Fc-receptor, and Ia-bearing cell type.
abstract: The nature of the accessory cell type required for the in vitro induction of antigen-specific helper T (Th) cells to soluble antigen was determined. Two different sources of adherent accessory cells were investigated: peritoneal exudate cells (PEC) and macrophages derived from bone-marrow cells (BMM phi), which were cultured for 8 days in vitro with colony-stimulating factor. PEC and BMM phi were rosetted with EA-SRBC and separated by sedimentation into Fc gamma receptor-positive and negative fractions. Only the Fc gamma receptor-positive fraction was active in Th-cell induction. By means of the fluorescence-activated-cell sorter (FACS-II), PEC or BMM phi were separated either into phagocytic and nonphagocytic, or Ia-positive and Ia-negative cell populations. Only phagocytic and Ia-positive accessory cells induced antigen specific Th cells. In conclusion, the accessory cell is adherent, phagocytic, carries Fc gamma-receptors and Ia products, and thus expresses the most important characteristics of the macrophage lineage.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology* / Q000276:immunology; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D006433:Hemocyanins / Q000276:immunology; D000949:Histocompatibility Antigens Class II; D007106:Immune Sera / Q000494:pharmacology; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008808:Mice, Inbred CBA; D010586:Phagocytes / Q000276:immunology*; D011817:Rabbits; D011961:Receptors, Fc; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; D007106:Immune Sera; D011961:Receptors, Fc; D006433:Hemocyanins