Down-regulation of tumoricidal NK and NK T cell activities by MHC Kb molecules expressed on Th2-type gammadelta T and alphabeta T cells coinfiltrating in early B16 melanoma lesions.
We examined whether gammadelta T and alphabeta T cells accumulating in early B16 melanoma lesions regulate NK and NK T cells that attack tumor cells. Freshly isolated and cultured tumor-infiltrating lymphocyte (TIL) populations of NK and NK T cells lysed B16 and produced IFN-gamma, whereas gammadelta T and a large part of alphabeta T cell populations had no substantial cytotoxicity against B16 and secreted Th2 cytokines. Furthermore, the freshly isolated NK1.1+ TIL population exhibited a higher anti-B16 effect than did splenocytes. Gammadelta T and alphabeta T cell populations dramatically inhibited the cytotoxicity of NK and NK T cells in an MHC Kb-dependent manner. Culture supernatant from gammadelta T and alphabeta T cell populations inhibited the proliferation of NK and NK T cell populations but did not affect their cytotoxicity, suggesting that the released Th2 cytokines are merely partly involved in the down-modulation of NK-lineage cells. NK1.1+ cells obtained from TIL of gammadelta T cell-depleted mice significantly lysed B16 cells compared with those from control mice. Finally, anti-Kb Fab mAb injected intralesionally at an early, but not at a late, stage of development of B16 melanoma inhibited tumor growth. These findings suggest that Th2-type gammadelta T and alphabeta T cells infiltrating in early B16 development inhibit the tumoricidal activity of NK-lineage cells using their class I molecules and partly their suppressive cytokines.
Department of Dermatology, Hamamatsu University School of Medicine, Japan. seo445@hama-med.ac.jp
N
N
Seo
Y
Y
Tokura
F
F
Furukawa
M
M
Takigawa
D000818:Animals; D003602:Cytotoxicity, Immunologic; D007694:Killer Cells, Natural / Q000276:immunology*; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology* / Q000473:pathology; D008285:Major Histocompatibility Complex / Q000276:immunology*; D008297:Male; D008546:Melanoma, Experimental / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology*
D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta