title: Accessory cell activity of murine tumor-associated macrophages.
abstract: The accessory cell activity of macrophages associated with the murine 3-methylcholanthrene-induced fibrosarcoma FSa was investigated. On the basis of Fc receptor expression and phagocytic activity, 20-25% of cells present within enzymatically disaggregated tumor cell suspensions could be classified as macrophages. These cells were approximately 50% I-Ak positive but did not express the Mac-1 antigen. T-cells played an important role in regulating I-Ak expression, and macrophages obtained from tumors grown in nu/nu mice were I-Ak negative. Tumor-associated macrophages were shown to possess potent accessory cell activity and were fully capable of reconstituting the primary anti-calf red blood cell plaque-forming cell (PFC) response of Sephadex G-10-passed spleen cells. This function required the presence of the I-Ak-positive subpopulation, and macrophages treated with anti-Ia serum and complement or obtained from tumors grown in nu/nu hosts lacked accessory cell activity. Tumor-associated macrophages were also able to provide the essential accessory cell function required for cooperation between tumor-specific TH cells and normal B-cells in the generation of an anti-trinitrophenyl (TNP) PFC response in the presence of TNP-coupled FSa antigen. These results suggest that progressive growth of the FSa tumor in vivo cannot be readily attributed to a defect in the accessory cell function of tumor-associated macrophages.
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D000954:Antigens, Surface / Q000032:analysis; D002469:Cell Separation; D002850:Chromatography, Gel; D006168:Guinea Pigs; D006462:Hemolytic Plaque Technique; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D016177:Macrophage-1 Antigen; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000276:immunology*; D010587:Phagocytosis; D011951:Receptors, Complement / Q000032:analysis; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D000949:Histocompatibility Antigens Class II; D016177:Macrophage-1 Antigen; D011951:Receptors, Complement