title: Variations in macrophage antigen phenotype: a correlation between Ia antigen reduction and immune dysfunction during tumor growth.
abstract: Variable Ia antigen expression by macrophages (M phi) was examined during tumor growth by measuring: Ia antigen masking and immunofluorescence by anti-Ia antibody, accessory cell function in concanavalin A (Con A) and mixed lymphocyte reaction (MLR)-induced T cell proliferation, and M phi stimulatory function in the MLR. Tumor-induced progressive loss of Ia antigen expression was shown by immunofluorescence and corroborated by anti-Ia blockade of MLR stimulatory activity of normal but not tumor-bearing hosts (TBH) splenic M phi. The TBH splenic M phi supported Con A-induced proliferation of syngeneic T cells (Ia antigen-independent) but did not support syngeneic T cell proliferation in the MLR (Ia antigen-dependent). Irrespective of tissue source, normal and TBH M phi differed in their MLR stimulatory capabilities. In general, splenic M phi preparations were better stimulators of allogeneic T cell blastogenesis in the MLR than thioglycollate-elicited peritoneal M phi. Kinetic studies with TBH M phi showed a significant progressive loss in MLR stimulatory activity, which was especially pronounced with peritoneal M phi. Expression of Ia antigens by normal but not TBH M phi were diminished by 24-h in vivo plating of the peritoneal M phi. Indomethacin treatment showed Prostaglandin E2 was not a direct in vitro factor in Ia antigen-mediated reduction of splenic M phi MLR stimulatory activity. Taken together, these data delineate a loss of M phi Ia antigen expression, resulting in a decrease in Ia antigen-mediated functional activities during tumor growth.
authors.forename: R E
authors.initials: RE
authors.lastname: Garner
authors.forename: A P
authors.initials: AP
authors.lastname: Malick
authors.forename: K D
authors.initials: KD
authors.lastname: Elgert
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000954:Antigens, Surface / Q000032:analysis; D002478:Cells, Cultured; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007213:Indomethacin / Q000494:pharmacology; D008213:Lymphocyte Activation; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D010529:Peritoneal Cavity / Q000276:immunology; D012513:Sarcoma, Experimental / Q000276:immunology*; D013154:Spleen / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D000949:Histocompatibility Antigens Class II; D007213:Indomethacin