POTENTIATION OF THE IMMUNE-RESPONSE IN HIV-1(+) INDIVIDUALS

T cells from HIV-1(+) individuals have a defect in mounting an antigen specific response. HIV-1 Tat has been implicated as the causative age nt of this immunosuppression. We have previously shown that HIV-1 Tat inhibits antigen specific proliferation of normal T cells in vitro by binding to the accessory molecule CD26, a dipeptidase expressed on the surface of activated T cells. We now demonstrate that the defective i n vitro recall antigen response in HIV-1 infected individuals can be r estored by the addition of soluble CD26, probably by serving as a deco y receptor for HIV-1 Tat. The restored response is comparable to that of an HIV-1(-) individual, suggesting that early in HIV infection ther e is a block in the memory cell response, rather than deletion of thes e cells.