title: Induction of tumor immunity by removing CD25+CD4+ T cells: a common basis between tumor immunity and autoimmunity.
abstract: This study shows that removal of a T cell subpopulation can evoke effective tumor immunity in otherwise nonresponding animals. Elimination of CD25-expressing T cells, which constitute 5-10% of peripheral CD4+ T cells in normal naive mice, elicited potent immune responses to syngeneic tumors in vivo and eradicated them. The responses were mediated by tumor-specific CD8+ CTLs and tumor-nonspecific CD4-8- cytotoxic cells akin to NK cells. Furthermore, in vitro culture of CD25+4+ T cell-depleted splenic cell suspensions prepared from tumor-unsensitized normal mice led to spontaneous generation of similar CD4-8- cytotoxic cells capable of killing a broad spectrum of tumors; reconstitution of CD25+4+ T cells inhibited the generation. In this culture, self-reactive CD25-4+ T cells responding to self peptides/class II MHC complexes on APCs spontaneously proliferated upon removal of CD25+4+ T cells, secreting large amounts of IL-2. The IL-2 thus produced appeared to be responsible for the generation of CD4-8- NK cells as lymphokine-activated killer cells, because direct addition of an equivalent amount of IL-2 to the culture of CD4-8- cells generated similar lymphokine-activated killer/NK cells, whereas coculture of normal CD4-8- cells with CD25-4+ T cells from IL-2-deficient mice did not. Thus, removal of immunoregulatory CD25+4+ T cells can abrogate immunological unresponsiveness to syngeneic tumors in vivo and in vitro, leading to spontaneous development of tumor-specific effector cells as well as tumor-nonspecific ones. This novel way of evoking tumor immunity would help to devise effective immunotherapy for cancer in humans.
authors.affiliation: Department of Immunopathology, Tokyo Metropolitan Institute of Gerontology, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Shimizu
authors.forename: S
authors.initials: S
authors.lastname: Yamazaki
authors.forename: S
authors.initials: S
authors.lastname: Sakaguchi
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D001327:Autoimmune Diseases / Q000276:immunology*; D015704:CD4 Antigens / Q000096:biosynthesis*; D002478:Cells, Cultured; D016219:Immunotherapy, Adoptive / Q000379:methods; D007275:Injections, Intravenous; D007942:Leukemia, Experimental / Q000276:immunology* / Q000628:therapy; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D008546:Melanoma, Experimental / Q000276:immunology* / Q000628:therapy; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D016513:Mice, SCID; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis* / Q000276:immunology; D012513:Sarcoma, Experimental / Q000276:immunology* / Q000628:therapy; D013154:Spleen / Q000166:cytology / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D015375:Receptors, Interleukin-2