title: Site of action of a soluble immune response suppressor (SIRS) produced by concanavalin A-activated spleen cells.
abstract: The cellular site of action of SIRS, a soluble immune response suppressor released by Con A-activated spleen cells which suppresses antibody responses to heterologous erythrocytes by murine spleen cells in vitro, was investigated. Exposure of spleen cells to SIRS for 2 hr at 37 degrees C or 1 hr at 4 degrees C was sufficient to suppress 5-day antibody responses in vitro. Similar exposure of splenic or peritoneal exudate macrophages to SIRS also suppressed antibody responses by untreated splenic lymphoid cells; exposure of splenic lymphoid cells to SIRS was without effect. SIRS did not act via T cells which might have contaminated the macrophage preparations. SIRS-mediated suppression could be partially overcome by an excess of normal peritoneal exudate macrophages, but not by an excess of T or B cells. These data indicate that the target cell of SIRS activity is the macrophage. The results are discussed in the context of macrophage functions that could be affected by SIRS.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D003208:Concanavalin A; D004912:Erythrocytes / Q000276:immunology; D006023:Glycoproteins / Q000494:pharmacology; D007165:Immunosuppression Therapy; D008214:Lymphocytes / Q000276:immunology; D008222:Lymphokines / Q000494:pharmacology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000276:immunology*; D013491:Suppressor Factors, Immunologic; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D006023:Glycoproteins; D008222:Lymphokines; D013491:Suppressor Factors, Immunologic; C013256:soluble immune response suppressor; D003208:Concanavalin A