Similarity of expression of activation markers and CD28 on gamma delta and alpha beta-receptor T cells in HIV infection.

During human immunodeficiency virus (HIV) infection, phenotypic analysis of circulating gamma delta+ T cells showed a downregulation of the CD28 surface antigen, as recently demonstrated for CD4+ and CD8+ alpha beta+ T cells. The downregulation of the CD28 molecule predominated on CD8+ gamma delta+ T cells. Moreover, an increased expression of CD38 and/or HLA-DR molecules was found on gamma delta T cells as reported for alpha beta T cells indicating that all categories of circulating T lymphocytes share similar phenotypic abnormalities in HIV-infected patients. These unique changes in the different T-cell subsets might be induced by sustained activation of the immune system or by the rapid turnover of T cells and argue for a global dysregulation of T lymphocytes during HIV infection.