Fas (CD95) expression on CD4+ T cells from HIV-infected patients increases with disease progression.

Active T cell suicide (apoptosis) is supposed to be involved in the CD4+ T cell depletion in the course of HIV infection. We investigated the expression of the apoptosis-related antigen Fas on CD4+ T cells from 25 HIV-positive individuals (CDC I-III) and 8 HIV-negative controls by two-colour flowcytometry. In addition, we evaluated: total CD4 count, HIV p24 antigen concentration in serum after immune complex dissociation, and clinical course of infection in HIV-positive individuals. We found a significant increase in mean Fas expression on CD4+ T cells from HIV-positive individuals compared to HIV-negative individuals (85.84 +/- 14.92% vs. 64.28 +/- 7.59%, P < 0.001). Within the HIV-positive group the increase in Fas expression was correlated with the decline in CD4 count (r = -0.76, P < 0.001), p24 antigen concentration in serum, after immune complex dissociation (r = 0.67, P < 0.001), and CDC stage (r = 0.73, P < 0.001). The upregulation of Fas antigen on CD4 cells is associated with CD4 depletion and other virological and clinical marker of disease progression in HIV infection.