title: Enhancement of human monocyte tumoricidal activity by recombinant M-CSF.
abstract: Activated monocytes are an important component of immunologic defense against neoplastic disease. A variety of agents capable of inducing tumoricidal activity have been described, including bacterial LPS, IFN-gamma, IL-1, IL-2, TNF, and GM-CSF. We now show that pretreatment of monocytes with recombinant human macrophage-specific colony stimulating factor (M-CSF) augments the tumoricidal activity of human peripheral blood monocytes induced by other activating agents. Monocytes were preincubated for three days with M-CSF at 10(3) U/ml, washed, and treated for an additional two days with secondary activators. Tumoricidal activity was measured in a 6-h 51Cr-release assay using NK-resistant WEHI 164 cells that had been treated with actinomycin D. Pretreatment of monocytes with M-CSF significantly increased tumoricidal activity induced by LPS, IFN gamma, LPS plus IFN gamma, and LPS plus PMA. Pretreatment with IL-1, IL-2, IL-3, IL-4, or GM-CSF was not as effective as M-CSF in increasing tumoricidal activity. Enhanced tumoricidal activity was directly correlated to the increased TNF production resulting from M-CSF pretreatment. TNF antiserum completely blocked tumoricidal activity, demonstrating that TNF was responsible for the M-CSF-mediated increase in tumor cell lysis. M-CSF pretreatment also enhanced non-TNF mediated tumoricidal activity by monocytes, as seen by increased killing of the TNF-resistant target P815. This study demonstrated that in addition to the role of M-CSF in the proliferation and differentiation of monocyte/macrophage precursors, M-CSF also augments an effector function of mature blood monocytes.
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D002460:Cell Line; D003115:Colony-Stimulating Factors / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D004306:Dose-Response Relationship, Immunologic; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D008262:Macrophage Activation / Q000187:drug effects; D009000:Monocytes / Q000187:drug effects / Q000276:immunology*; D011994:Recombinant Proteins / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D000276:Adjuvants, Immunologic; D003115:Colony-Stimulating Factors; D006133:Growth Substances; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D016178:Granulocyte-Macrophage Colony-Stimulating Factor