FIG. 5.

Noncytotoxic features of HIV-suppressing CD8⁺ cells. (A) HIV replication levels were evaluated in cultures from which CD8⁺ cells were removed following suppression of HIV replication. Shown are reverse transcriptase (RT) levels in the supernatants of HIV-infected cells cultured alone (▪), in the presence of HIV-suppressing CD8⁺ cells (•), and upon removal of the HIV-suppressing CD8⁺ cells after 4 days of coculture (★). (B) CD107a/CD107b levels were measured in HIV-specific CD8⁺ cells (left) and bulk CD8⁺ cells (right) upon exposure to cognate antigen and heterologous HIV-infected CD4⁺ cells, respectively. (C) CD8⁺ cells from a viremic HIV-infected individual were sorted into 2 subsets: CD57⁻ PD1⁺ cells and those lacking this phenotype (not CD57⁻ PD1⁺). Conditioned medium collected from cultures containing these CD8⁺ cell subsets was placed onto CD4⁺ cells that were acutely infected with HIV. Shown are the RT levels in each culture at the time of peak virus replication in the control. Data in each panel are representative of at least 2 separate experiments.