title: Ia antigen expression and IL-1 activity in murine tumour-associated macrophages.
abstract: Tumour-associated macrophages (TAM) isolated from five murine sarcomas had a relatively high frequency of I-A+ cells, with mean values of 27% (mFS6), 52% (MN/MCA1), 68% (N3), 62% (N4) and 98% (J3) for TAM compared to 12% for resident peritoneal macrophages. Expression of I-E in TAM was also high (29%) in the only sarcoma (N4) examined in this respect. Expression of I-A by TAM declined in culture but exposure to lymphokine supernatants maintained and increased the frequency of I-A+ cells in TAM. Transplantation of tumours into nude mice caused a marked decrease in the percentage of I-A+ TAM in the case of the N4 sarcoma (8% compared to 48%), whereas for the MN/MCA1 sarcoma the diminution was only marginal (from 53 to 41%), TAM from murine sarcomas did not constitutively release appreciable levels of interleukin-1 (IL-1) activity. Upon stimulation with bacterial lipopolysaccharides or silica, TAM showed a limited capacity to produce and release IL-1 activity compared to peritoneal macrophages. Thus the expression of I-A antigens and the IL-1-producing capacity are uncoupled in TAM from murine sarcomas. These properties of TAM could play an important role in the generation of anti-tumour immunity and/or of suppressive T-cell circuits.
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000951:Antigens, Neoplasm / Q000032:analysis*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000032:analysis*; D007375:Interleukin-1 / Q000096:biosynthesis*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D012513:Sarcoma, Experimental / Q000276:immunology*
chemical_list: D000951:Antigens, Neoplasm; D000949:Histocompatibility Antigens Class II; D007375:Interleukin-1