Representative dot plots of HIV tetramer–positive CD8 T cells stained for markers associated with cytotoxic function.

Samples from HIV-infected, long-term asymptomatic donor CW5 (A) and healthy donors (B-C) were stained for CD8, indicated tetramer, and perforin, GzmA, CD27, or CD45RA. The left panel of each row depicts the dot plot after gating tightly on lymphocytes; all other panels are gated on CD8^brightlymphocytes. In the HIV-infected donor, HIV-specific cells are CD27⁺ and CD45RA⁻, whereas the EBV- and CMV-specific cells in the same donor are more heterogeneous in their expression of these markers. The sample in panel B from a healthy donor was one of the few samples with a high frequency of perforin-staining, tetramer-positive cells.