Alternative complement pathway activation by CD4+ T cells of HIV infected individuals: a possible role in AIDS pathogenesis.

The mechanisms by which CD4+ T cells are eliminated during HIV infection are poorly understood. We have previously shown that HIV infected cell lines activate and fix C3 via the alternative complement pathway (ACP). In the present study we examined the ability of blood lymphocytes from 40 HIV+ individuals to fix C3. A large fraction of the CD4+ T cells reacted with anti-gp120 antibodies. These cells also carried C3 fragments in vivo and could further fix C3 if exposed to human serum in vitro. C3 activation occurred via the ACP. In some cases exposure of the lymphocytes to human serum under conditions allowing ACP activation resulted in partial elimination of CD4+ T cells. The results suggest that complement activation and fixation by CD4+ T cells opsonized with HIV particles or gp120 may contribute to their selective destruction.