title: Failure to reject an allografted tumor after elimination of macrophages in mice.
abstract: After an i.p. transplantation of an allogeneic tumor (Meth A) to C57BL/6 mice, a macrophage (M phi)-rich, non-T, non-NK cell population is induced as the major infiltrate and cytotoxic cells. We here evaluated the role of the M phi s in the rejection of allografted Meth A cells and characterized the M phi s in comparison with other well-known M phi s. At all time intervals after transplantation, the highest cytotoxic activities against Meth A tumor were obtained with the M phi-rich population. In addition, the lymphocyte-rich population had a significant but low cytotoxic activity, whereas two other population types, granulocytes and large granular cells, were inactive. When the M phi-rich or the T cell-depleted M phi-rich population was i.p. transplanted simultaneously with Meth A cells into untreated C57BL/6 mice, the tumor cells were rejected without growth. After specific elimination of M phi s by in vivo application of dichloromethylene diphosphonate-containing liposomes, the cytotoxic activity against Meth A cells was hardly induced at the transplantation site of Meth A cells and the allografted Meth A tumor continued to grow, indicating that a type of M phi is the effector cell essential for the rejection. In contrast to other well-known M phi s, the cytotoxic activity against Meth A cells was cell-to-cell contact dependent and soluble factor (e.g., NO and TNF-alpha) independent. Moreover, the cytotoxic activity of the M phi s (H-2b) against 51Cr-labeled Meth A (H-2d) cells was inhibited by the addition of unlabeled H-2d, but not H-2b, H-2k or H-2h, lymphoblasts as well as Meth A cells, implying the specific interaction of the M phi s with H-2d cells.
authors.affiliation: Department of Cell Biology, Osaka Bioscience Institute, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ushio
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
authors.forename: A
authors.initials: A
authors.lastname: Sanchez-Bueno
authors.forename: R
authors.initials: R
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D002450:Cell Communication; D004002:Clodronic Acid / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D005354:Fibrosarcoma / Q000276:immunology*; D006084:Graft Rejection / Q000276:immunology*; D007165:Immunosuppression Therapy; D008081:Liposomes / Q000494:pharmacology; D008212:Lymphocyte Depletion; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation / Q000276:immunology*; D010529:Peritoneal Cavity / Q000601:surgery; D010537:Peritoneum / Q000276:immunology; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014184:Transplantation, Homologous
chemical_list: D008081:Liposomes; D004002:Clodronic Acid