Prognostic value of HIV-1 Gag-specific CD4+ T-cell responses for progression to AIDS analyzed in a prospective cohort study.

The causal relationship between HIV-specific CD4+ T-cell responses and viral control and the effect of these responses on the natural history of HIV infection is unclear. In a detailed longitudinal study, functional HIV-1 Gag-specific CD4+ T cells were analyzed in long-term asymptomatic individuals (LTA; n = 6) and progressors to AIDS (n = 7) with a median follow-up of, respectively, 118 and 57 months. Next, HIV-specific CD4+ T-helper cell responses were measured in a prospective cohort study among 96 HIV seroconverters and were related to clinical endpoints using Cox proportional hazard analyses. In the detailed study, no difference for HIV-specific helper-cell responses between LTAs and progressors was observed early in infection, but Gag-specific CD4+ T cells producing IL-2 or IFNgamma were lost in progressors late in infection. Multivariate proportional hazard analyses in the prospective cohort study showed that HIV-specific IL-2+, IFNgamma+, or IL-2+IFNgamma+ CD4+ T cells early after seroconversion had no prognostic value for the rate of progression to AIDS. Our results are compatible with viral load determining the nature and magnitude of HIV-specific CD4+ T-cell responses, rather than HIV-specific CD4+ T-cell responses controlling HIV plasma viral load.