[Apoptosis induction and its mechanism in HIV infection]

Evidence is accumulating that apoptotic pathways account for the depletion of CD4 T cells in HIV-1 infected individuals. These pathways may be mediated, either directly by a virus infection or indirectly, through the priming of uninfected cells to apoptosis, when triggered by different agents. The participation of apoptosis in the cytopathic effect of CD4 T cells infected with HIV, in vitro, has already been shown. In our study using human CD4 cell clones expressing gp160 of HIV-1 under the control of inducible promoter, cell killing due to apoptosis was induced in the cells when gp160 was synthesized and a complex formed with gp160 in the cell. Non-infected CD4 T cells present in the vicinity of an infected cell may be killed through several mechanisms that involve gp120-CD4 interactions. Gp120 shed from infected cells can interact with CD4 on non-infected cells. Cross-linking of CD4 by such gp120 or by further binding of anti-gp120 antibody to gp120 may prime CD4 T cells for apoptosis following antigen-driven activation.