Figure 2: The immunization strategy elicited mucosal long term memory T-cell immune responses. Production of IFN- by CD3+CD4+ or CD3+CD8+ memory T cells isolated from colon was analyzed in the vaccinated macaques one year after final peptide-cocktail boost. Lamina propria lymphocytes (LPL) from colon biopsy samples were stimulated with peptide-mix or mitogens for 6 h. Both untreated (control) and stimulated cells were stained for surface markers, followed by fixation, permeabilization, and intracellular staining of IFN-. Live cells were identified by gating on Aqua-negative cells. The cells gated on CD3+CD4+ and CD3+CD8+ were further separated as memory population according to the expression of CD95 (data not shown). The percentage values indicate the population of IFN-—producing CD3+ CD95+CD4+ or CD3+ CD95+CD8+ lymphocytes.