Inhibitory potential of subpopulations of CD8⁺ T cells in HIV-1-infected elite suppressors

Elite controllers or suppressors (ES) are HIV-1-infected individuals who suppress viral replication to clinically undetectable levels without antiretroviral therapy. Understanding the mechanisms by which ES control viral replication may prove informative for the design of a therapeutic vaccine. Qualitative differences in the CD8⁺ T cell response have been implicated in control. Therefore, we isolated CD⁺ T cells from ES and characterized the ability of sorted memory and activation subpopulations to control viral replication at various effector-to-target cell ratios using a novel modification of a CD8⁺ T cell suppression assay. The effector memory and terminal effector subpopulations of memory CD8⁺ T cells had the highest inhibitory potential over the course of a 3-day in vitro infection. Interestingly, after 5 days of infection, central memory CD8⁺ T cells were also very effective at suppressing viral replication. No significant correlation between the suppression of viral replication and the number of HIV-1-specific CD8⁺ T cells was observed. HLA-DR^- CD38⁺ CD8⁺ T cells possessed the lowest inhibitory potential of the activation subpopulations. Taken together, our data suggest that there are key differences in the magnitude and kinetics of the suppression of HIV-1 replication by different CD8⁺ T cell subsets. These data should guide the development of an effective, cellular therapeutic vaccine that has the potential to elicit similar CD8⁺ T cell responses.