IDENTIFICATION AND CHARACTERIZATION OF RAT GAMMA DELTA T-LYMPHOCYTES IN PERIPHERAL LYMPHOID ORGANS, SMALL-INTESTINE, AND SKIN WITH A MONOCLONAL-ANTIBODY TO A CONSTANT DETERMINANT OF THE GAMMA/DELTA T-CELL RECEPTOR/

A mAb called V65 was raised to a CD3(+), TCR-alpha/beta(-) rat/mouse T cell hybrid that selectively reacts with all CD3(+) TCR-alpha/beta(-) rat lymphocytes. Both anti-CD3 and V65 precipitate a 48- to 50-kDa he terodimeric protein from digitonin-lysed surface-iodinated cells. V65( +) but not V65(-) T cells and T cell hybridoma cells express TCR-gamma mRNA. Together, these results show that V65 detects a constant determ inant of the rat TCR-gamma/delta. In the presence of either IL-2 or IL -4, V65 stimulates proliferation in peripheral rat gamma/delta T cells . Approximately 90% of gamma/delta T cells from peripheral lymphoid or gans have the same cell surface phenotype as thymus-derived MHC class I-restricted alpha/beta T cells, i.e., they are CD4(-) but express the CD8 alpha/beta heterodimer together with CD2 and CD5. In contrast, ga mma/delta T cells from the epithelium of the small intestine lack CD2, CD4, and CD5 and express CD8 alpha only. Finally, V65 directly identi fies a dense network of dendritic cells in the epidermis as gamma/delt a T cells. These dendritic epidermal T cells are absent from athymic r ats, indicating that like their mouse counterparts, they are thymus de pendent.