HIV-specific T cell responses are highly stable on antiretroviral therapy

Abstract HIV infection induces a robust T cell response that is sustained by high viremia, but falls following the onset of ART. Relatively little has been reported on the subsequent stability of the HIV-specific T cell response in individuals on durable therapy. Such data are critical for powering clinical trials testing T cell based immunotherapies. In a cross-sectional study, HIV-specific T cell responses were detectable by ex vivo IFN-γ ELISpot (average ∼ 1,100 SFU/106 peripheral blood mononuclear cells) in persons living with HIV (PLWH, n=34), despite median durable ART suppression of 5.0 years. No substantial association was detected between the summed HIV-specific T cell response and the size of the replication competent HIV reservoir. T cell responses were next measured in participants sampled weekly, monthly, or yearly. HIV-specific T cell responses were highly stable over the time periods examined; within-individual variation ranged from 16% coefficient of variation (CV) for weekly to 27% CV for yearly sampling. These data were used to generate power calculations for future immunotherapy studies. The stability of the HIV-specific T cell response in suppressed PLWH will enable powered studies of small sizes (e.g., n=6 to 12), facilitating rapid and iterative testing for T cell-based immunotherapies against HIV.