Interleukin 7 reduces the levels of spontaneous apoptosis in CD4+ and CD8+ T cells from HIV-1-infected individuals

Apoptosis has been suggested as one of the major mechanisms of CD4(+) T cell depletion during the course of HIV type 1 (HIV-1) infection. Here, we show that interleukin 7 (IL-7), a nonredundant cytokine that plays essential roles in the generation and homeostasis of the T cell compartment of the immune system, exerts strong antiapoptotic effects ex vivo on both CD4(+) and CD8(+) T cells derived from HIV-1-infected subjects. The level of IL-7-mediated reduction of apoptosis was inversely correlated with the number of circulating CD4(+) T cells, indicating a higher sensitivity to IL-7 effects in patients with more advanced disease. The antiapoptotic effect of IL-7 was uncoupled from the induction of cellular proliferation or endogenous HIV-1 replication. These results provide a further rationale for consideration of IL-7 as an agent of immune reconstitution in HIV-1 infection.