V delta and V delta 2 gamma delta T cells express distinct surface markersand might be developmentally distinct lineages

We report here that the two major types of gamma delta T cells found in hum an blood, V delta1 and V delta2, were found to have markedly different phen otypes. V delta2 cells had a phenotype typical of most up T cells in blood; i.e., they were CD5(+), CD28(+), and CD57(-). In contrast, V delta1 cells tended to be CD5(-/dull), CD28(-), and CD57(+). Furthermore, although V del ta1 T cells appeared to be "naive" in that they were CD45RA(+), they were C D62L(-) and on stimulation uniformly produced interferon-gamma, indicating that they are in fact memory/effector cells. This phenotype for V delta1 ce lls was similar to that of intestinal intraepithelial lymphocytes, a subset that can develop in the absence of the thymus. We suggest that the V delta 1 and V delta2 T cell subsets represent distinct lineages with different de velopmental pathways. The disruption of the supply of normal, thymus-derive d T cells in HIV-infected individuals might be responsible for the shift in the V delta2/V delta1 ratio that occurs in the blood of individuals with H IV disease.