title: B cell stimulatory factor-1 (interleukin 4) activates macrophages for increased tumoricidal activity and expression of Ia antigens.
abstract: Macrophages are activated by lymphokines (LK) to kill tumor cell and microbial targets. Interferon-gamma (IFN) is the major LK activity in conventional, antigen or mitogen-stimulated spleen cell culture fluids for induction of these macrophage effector functions. In view of the recent demonstration that murine macrophage-like cell lines have receptors for B cell stimulatory factor-1/interleukin 4 (BSF-1), a possible role for BSF-1 in regulation of macrophage function was considered. In this communication, thioglycollate-elicited murine peritoneal macrophages were shown to express about 2300 high affinity (Ka approximately 2 X 10(10) M-1) BSF-1 receptors/cell. Peritoneal macrophages treated with purified, T cell-derived BSF-1 developed potent tumoricidal activity against fibrosarcoma target cells. The concentration of BSF-1 that induced 50% of maximal tumor cytotoxicity was 38 +/- 4 U/ml for seven experiments; similar dose-responses were observed with recombinant BSF-1. That BSF-1 dose-responses for induction of macrophage-mediated tumor cytotoxicity were not affected by 5 micrograms/ml polymyxin B suggested that contaminant endotoxins played little or no role in cytotoxic activity. BSF-1 alone (less than or equal to 500 U/ml) was not directly toxic to tumor cells or macrophages. Macrophage tumoricidal activity induced by BSF-1 but not by IFN was inhibited greater than or equal to 90% with monoclonal anti-BSF-1 antibody. BSF-1 induced Ia antigen expression on peritoneal macrophages and increased (twofold to threefold) FcR(II)-dependent binding of murine IgG immune complexes to bone marrow-derived macrophages (greater than 98% macrophages). Based on these findings, it was concluded that BSF-1 is a potent macrophage activation factor.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006133:Growth Substances / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000502:physiology; D015847:Interleukin-4; D008222:Lymphokines / Q000494:pharmacology / Q000502:physiology*; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000276:immunology; D011961:Receptors, Fc / Q000378:metabolism*; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D006133:Growth Substances; D000949:Histocompatibility Antigens Class II; D008222:Lymphokines; D011961:Receptors, Fc; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen; D011994:Recombinant Proteins; D015847:Interleukin-4; D007371:Interferon-gamma