IL-10 inhibits HIV-1 replication and is induced by tat.

Interleukin 10 (IL-10) is produced by TH2 lymphocytes and regulates both lymphoid and myeloid cells. In the present study we demonstrate that IL-10 is expressed and produced spontaneously in the peripheral blood mononuclear cells (PBMCs) of all HIV-1 infected individuals tested, 3 of 19 cases of HIV-negative lymphoma and none of five healthy controls. IL-10 mRNA was detectable in both monocytes/macrophages and T lymphocytes isolated from PBMCs of HIV infected patients. We have also shown that infection of promonocytic (U937) and T (H9) cell lines with HIV stimulates IL-10 secretion. Furthermore, a T cell line (H9) stably transfected with a HIV tat expression-vector secreted higher levels of IL-10. We have also demonstrated that rhIL-10 inhibited HIV-1 replication in infected monocytes and PBMCs in a dose dependent manner. IL-10 may thus participate in long latency between HIV-1 infection and development of AIDS.