CD8A and AIDS: To investigate a possible correlation between in vitro cytokine production and AIDS-free survival time, the frequency of single IFNγ producing (Fig. 2A), single IL-2 producing (Fig. 2B) and double IFNγ+IL-2 producing (Fig. 2C) Gag-specific CD8+ T cells was plotted against the AIDS-free survival time of the study participants.