Changes in function of HIV-specific T-cell responses with increasing time from infection

Recently HIV-infected individuals have virus-specific responses characterized by IFN-γ/IL-2 secretion and proliferation rarely seen in chronic infection. To investigate the timing of loss of HIV-specific T-cell function, we screened cells from 59 treatment-naïve HIV-infected individuals with known dates of infection for proteome-wide responses secreting IFN-γ/IL-2 and IFN-γ alone by ELISPOT. HIV peptide-specific proliferation was assessed by carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution. The contribution of IFN-γ/IL-2 and IFN-γ-only secretion to the total HIV-specific response was compared in subjects infected <6, 6-12, and 12-36 mo earlier. The frequency of IFN-γ/IL-2-secreting cells fell, while that of IFN-γ-only secretion rose with time from infection. HIV peptide-specific proliferative responses were almost exclusively mediated by CD8⁺ T cells, and were significantly lower in cells obtained from the 12-36 mo versus < 6 mo post-infection groups. By the second year of infection there was a significant difference in these functions compared to those assessed within 6 mo.