title: Immunosuppressive activity of cloned natural killer (NK1.1+) T cells established from murine tumor-infiltrating lymphocytes.
abstract: To elucidate the role of NK1.1+ T cells in the antitumor immune response, we established cloned NK1.1+ T cell lines from tumor-infiltrating lymphocytes (TIL) of B16 melanoma, and examined their mode of action in generating antitumor effector T cells both in vitro and in vivo. An NK1.1+ T cell clone (TM4.2) was phenotypically CD3+ TCR-alphabeta+ CD4- CD8- NK1.1+, and CD28+. The TM4.2 cells suppressed the in vitro generation of anti-B16 melanoma CTLs, but not the effector function of CTLs. The results using a transwell membrane suggested that their suppressive activity was mediated by both soluble factors and a direct cell to cell interaction. As for the soluble factors, the suppressive activity of the culture supernatant of TM4.2 cells was neutralized by anti-TGF-beta mAb, and the TM4.2 cells actually produced a considerable amount of TGF-beta. On the other hand, the TM4.2 cells showed a high level of cytolytic activity against B cell blasts and CD80-transfected P815, and such cytolytic activity was reduced by the addition of anti-CD80 mAb. In addition, NK1.1+ T cells in the freshly isolated TIL were revealed to express CD28. Furthermore, the TM4.2 cells suppressed the in vitro generation of anti-allo CTLs irrespective of the MHC haplotype. Finally, the TM4.2 cells suppressed the in vivo antitumor immune response. Collectively, these findings demonstrate that NK1.1+ T cells in TIL show immunosuppressive activity in the antitumor immune response through the production of TGF-beta and the preferential cytolysis of B7-expressing cells.
authors.affiliation: Department of Immunology, Medical Institute of Bioregulation, Kyushu University, Higashi-ku, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tamada
authors.forename: M
authors.initials: M
authors.lastname: Harada
authors.forename: K
authors.initials: K
authors.lastname: Abe
authors.forename: T
authors.initials: T
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Tada
authors.forename: Y
authors.initials: Y
authors.lastname: Onoe
authors.forename: K
authors.initials: K
authors.lastname: Nomoto
mesh_terms: D000818:Animals; D018122:B7-1 Antigen / Q000502:physiology; D018106:CD28 Antigens / Q000502:physiology; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D007108:Immune Tolerance; D007111:Immunity, Cellular; D016130:Immunophenotyping; D007694:Killer Cells, Natural / Q000276:immunology*; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008546:Melanoma, Experimental / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
chemical_list: D018122:B7-1 Antigen; D018106:CD28 Antigens; D016212:Transforming Growth Factor beta