FIG. 7.

Cytolytic markers of NK cells in response to Vpu peptide. Serum from subject 26 was incubated with either control dimethyl sulfoxide or the HIV-1 Vpu peptide 19 epitope and HIV-negative donor PBMCs for 6 h. NK cells (CD3⁻ CD2⁺ CD56⁺ gated lymphocytes) were examined for surface expression of the degranulation marker CD107a and intracellular expression of the cytolytic effector molecules granzyme B and perforin. There was significant CD107a expression in response to Vpu, and the cells with highest expression of CD107a also lost intracellular granzyme B and perforin. Percentages of CD107a⁺ granzyme B-negative and CD107a⁺ perforin-negative cells are shown in the lower-right quadrants.