In vitro HIV-specific CTL activity from HIV-seropositive individuals is augmented by interleukin-12 (IL-12)

IL-12 production is reduced in HIV infection, and recombinant human IL-12 ( rhIL-12) augments in vitro HIV-specific proliferative responses in PBMC fro m HIV-seropositive individuals. To determine whether rhIL-12 could also aug ment HIV-specific CTL responses we studied 41 HIV-seropositive individuals. Recombinant hIL-12 increased the detectable in vitro HIV-specific CD8 CTL activity of PBMC taken from HIV-seropositive individuals with CD4 counts >5 00 cells/mul and from some individuals with lower CD4 counts. IL-12 increas ed cell recovery in cultures of PBMC from HIV-seropositive individuals with CD4 counts >500 cells/mul and also increased the precursor CTL frequency. However, the increase in HIV-specific CTL activity was not due to IL-2 or I FN-gamma production or an increase in the number of cells with surface mark ers characteristic of CTL effector cells. This study demonstrates that rhIL -12 augments in vitro HIV-specific CTL activity and provides evidence to ju stify further investigation within clinical trials of this cytokine in HIV infection.