Cytotoxic monocytes in the blood of HIV type 1-infected subjects destroy targeted T cells in a CD95-dependent fashion.

HIV-1 infection changes the functional balance of macrophages in the body; it inhibits the development of macrophages capable of costimulating T cell responses and it favors the development of macrophages that kill T cells with which they form cellular conjugates. Cytotoxic macrophages destroy CD4 T cells, which they target through CD4-reactive immune-complexed HIV-1 envelope molecules on a large scale. They also destroy T cells that they target through presented antigen or mitogen. We show here that cytotoxic macrophages destroy their cellular targets at least partially in a CD95-dependent process in which T cells first modulate expression of most of their membrane receptors and subsequently die.