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 HIVinfection are poorly understood. We have previously shown thatHIV infected cell lines activate and fix C3 via the alternativecomplement pathway (ACP). In the present study we examined theability of blood lymphocytes from 40 HIV⁺ individuals to fixC3. A large fraction of the CD4⁺ T cells reacted with anti-gp120antibodies. These cells also carried C3 fragments in vivo andcould further fix C3 if exposed to human serum In vitro. C3activation occurred via the ACP. In some cases exposure of thelymphocytes to human serum under conditions allowing ACP activationresulted in partial elimination of CD4⁺ T cells. The resultssuggest that complement activation and fixation by CD4⁺ T cellsopsonized with HIV particles or gp120 may contribute to theirselective destruction.