Anti-CD95 (APO-1/Fas) autoantibodies and T cell depletion in human immunodeficiency virus type 1 (HIV-1)-infected children

Advanced stages of HIV-1-infection are characterized by progressive CD4+ T cell depletion. Peripheral T cells from HIV-1+ donors show accelerated apoptosis in vitro. The CD95 (APO-1/Fas) receptor/ligand system is involved in this process. To further study deregulation of the CD95 system in peripheral T cells during HIV-1-infection, we measured CD95-expression on CD4+ and CD8+ T cells together with serum levels of soluble CD95 (sCD95) and anti-CD95 autoantibodies in HIV-1+ children and healthy controls. Anti-CD95 levels in HIV-1+ children were significantly elevated when compared to uninfected controls, whereas serum levels of sCD95 were not different. In HIV-1+ children, CD95-expression on CD4+ and CD8+ T cells increased with age. A strong correlation between depletion of CD4+ cells in vivo and increase in CD95-expression on CD4+ T cells was observed. In contrast, such a correlation was not found for CD8+ T cells. A negative correlation between anti-CD95 autoantibody levels and CD4+ T cell counts, that was predicted by multiple linear regression analysis of pooled data, was found in individual patients observed longitudinally by repeated measurements. Since anti-CD95 autoantibodies isolated from HIV-infected adults have previously been shown to induce apoptosis of sensitive target cells in vitro, we speculate that the interaction of these antibodies with CD95-positive and CD95-sensitive T cells in vivo might be involved in progressive T cell loss during HIV-1-infection.