Induction of murine gamma delta T cells cytotoxic for xenogeneic rat cells.

C57BL/6 mice deprived or nondeprived of CD4+ and CD8+ T cells by mAbs were challenged with a rat T cell line, W7TM-1. Spleen cells obtained from CD4- and CD8-depleted animals rejecting W7TM-1 were examined by cytofluorometry, which demonstrated the presence of highly increased gamma delta type CD4-CD8- T cell population (30 to 50% of entire T cells). In vitro sensitization of these spleen cells with W7TM-1 generated a mixture of gamma delta and alpha beta type CD4-CD8- CTL for W7TM-1. Repeated stimulation of these cells with W7TM-1 resulted in a gamma delta-type T cell population with more than 95% purity by day 45. In contrast, alpha beta type CD8+ CTL for W7TM-1 were induced from mice nondeprived of CD4+ and CD8+ T cells. Both gamma delta-type CD4-CD8- CTL and alpha beta type CD8+ CTL were cytotoxic for rat cells in a species-specific manner. However, only reactivity of gamma delta type CD4-CD8- CTL, but not alpha beta type CTL, was inhibited by a mAb for TCR-gamma delta. The gamma delta type CD4-CD8- CTL clones were also prepared from spleen cells derived from CD4- and CD8-depleted mice. They were also reactive for xenogeneic cells in a species-specific manner. Spleen cells derived from CD4- and CD8-depleted mice rejecting the whole-layer rat skin grafts were in vitro sensitized with rat spleen cells, which also generated gamma delta type CD4-CD8- CTL specific for rat cells. V gamma 1 was detected as a major V gamma gene expressed in this gamma delta population by reverse transcriptase-PCR. Cytotoxicity for xenogeneic cells may represent one of major function of gamma delta T cells.