Homing of transgenic gammadelta T cells into murine vaginal epithelium

The vaginal epithelium of normal mice contains lymphocytes of fetal thymic origin that express an invariant Vgamma4/Vdelta1 TCR. The apparent lack of other gammadelta TCR species suggests that a selection mechanism might operate to regulate the localization of gammadelta T cells at this anatomical site. Selection might be connected to the Vgamma4/Vdelta1 TCR or to some homing characteristic of the fetal thymic lineage that appears at day 17-18 of embryonic life. In the present studies, we investigated whether transgenic gammadelta cells expressing a TCR species characteristic of the subpopulation of gammadelta T cells found in the blood, spleen and lymph would translocate to the vaginal epithelium. We found that the transgenic Vgamma2 TCR+ cells did accumulate in the vagina of transgenic mice. Furthermore, like normal vaginal gammadelta T cells, the transgenic vaginal gammadelta T cells expressed the phenotype of recently activated memory/effector T cells (CD44(hi), CD62L-, CD45RB(lo), CD69+). Vaginal gammadelta T cells in normal mice do not express the CD2 and CD28 antigens, but both of these markers are present on transgenic vaginal gammadelta T cells. We observed that a small fraction of splenic transgenic gammadelta T cells had the same surface phenotype as the vaginal transgenic gammadelta T cells, raising the possibility that the gammadelta T cells present in the vaginal epithelium of transgenic mice originated from the peripheral lymphoid organs. Data in support of this possibility came from experiments in which co-incubation of splenic transgenic gammadelta T cells with vaginal epithelial cell suspensions induced the vaginal gammadelta phenotype on the splenic gammadelta T cells. The finding of transgenic gammadelta T cells in the vaginal epithelium suggests that homing of gammadelta T cells to this site is not restricted to gammadelta T cells that express the V4/NS1 invariant TCR. Furthermore, these findings imply that retention of gammadelta T cells in the vaginal epithelium of normal mice is affected by a Vgamma4/Vdelta1-specific mechanism. The finding of a significant level of apoptosis in the transgenic vaginal gammadelta T cells, but not in the normal vaginal gammadelta T cells, could reflect that the mechanism of retention of Vgamma4/Vdelta1 + in the vaginal epithelium involves selective survival at the site.