EXPRESSION OF THE FAS ANTIGEN IN PATIENTS INFECTED WITH HUMAN-IMMUNODEFICIENCY-VIRUS

Lymphocytes from patients with HIV infection have been shown to underg o accelerated apoptosis. Fas antigen is a cell surface protein known t o initiate an apoptotic signal. Therefore, we undertook a study to exa mine the expression of the Fas antigen during HIV infection. Using thr ee color flow cytometry, expression of the Fas antigen on lymphocytes of 23 HIV infected individuals (CDC category 2, CD4 200-499 cells/mu L , n = 10; CDC category 3, CD4 < 200 cells/mu L, n = 13) and 10 healthy controls was examined. Both CD3(+)CD4(+) and CD3(+)CD8(+) subsets wer e examined for their expression of this marker. In lymphocytes of heal thy controls, 47% of the CD3(+)CD4(+) and 45% of the CD3(+)CD8(+) cell s were Fas antigen positive. This percentage was significantly increas ed in CD4 cells from HIV infected patients belonging to CDC category 3 , but was unchanged from normal values in CDC category 2 subjects. The increase in the percentage of CD4(+) T cells expressing Fas antigen i n patients correlated significantly with the decrease in circulating C D4 T cell count (P < 0.009). In addition, by examining mean fluorescen ce intensity, we found that the amount of Fas expression per cell was increased threefold in CD3(+)CD4(+) cells and increased twofold in CD3 (+)CD8(+) cells in category 3 patients. These results demonstrate that an increase in Fas antigen expression occurs during HIV infection. (C ) 1995 Wiley-Liss, Inc.