Early changes in peripheral blood T cell subsets induced by antiretroviral treatment of human immunodeficiency virus-1 positive individuals.

Human immunodeficiency virus (HIV)-1 infection causes a gradual decline in peripheral blood CD4+ T cells. Shortly after the primary infection, an expansion of the activated memory CD8+ T-cell pool is also observed paralleling increased levels of plasma viraemia. In the present study we investigated the immediate effects of zidovudine therapy on peripheral blood T-cell subsets during the first 3 weeks of therapy in a group of HIV-1 positive individuals receiving influenza vaccine. HIV-1 positive individuals who received vaccine, but no treatment, were included as controls. Both the number of CD4+ and CD8+ T cells increased during the first week of therapy in parallel with a decline in plasma viraemia. The majority of CD4+ T cells contributing to this expansion expressed CD28, CD45RO and Fas, whereas the expanded CD8+ T cells were predominantly CD28-, CD45RO+, CD38+, Fas+ and Fas+ (CD95). We propose that the increase in the number of activated memory T cells observed in peripheral blood immediately after the onset of antiretroviral treatment is most likely caused by the redistribution of cells from various lymphoid organs in response to decreased levels of viral load in these compartments. The degree of T-cell redistribution is probably dependent on the magnitude of virus suppression.