Polyfunctional profile of CD4+ T cells.

PBMCs isolated 2 weeks after the fourth immunization were stimulated in vitro with a SIVpol peptide pool mix for 5 hours. Cells were stained for intracellular production of IFN-γ, TNF-α and IL-2 and degranulation by CD107a. The magnitude of the SIVgag (white), env (grey) and pol (black) responses are shown as stacked means ± SEM for each group (a). The percentage of the total functional response that has a CD28CD95+ (black bar) or CD28+CD95+ (white bar) is shown as group means ± SEM (b). Pie charts show the proportion of antigen-specific CD4+ T cells that have 4 functions (purple), 3 functions (yellow), 2 functions (green) or 1 function (light blue) (c). The bar graphs depict the absolute frequency of each of the 15 functional combinations for the DNA (red), 4-1BB (blue), CTLA-4 (orange), Combo (green) and Saline (black) groups in response to SIVgag, env, and pol after background subtraction (d).