FIG. 5.

Gag-specific CD4⁺ T-cell proliferative responses in the chronic phase. PBMCs around week 30 postchallenge were stimulated with p55, and specific uptake of BrdU in CD4⁺ T cells was examined. (A) Frequencies of Gag-specific BrdU⁺ CD4⁺ T cells in total CD4⁺ T cells. The frequencies in NAb-immunized macaques were significantly higher than in unimmunized controls (P = 0.042). (B) A representative density plot (gated on CD3⁺ lymphocytes) showing BrdU⁺ CD4⁺ T-cell induction after Gag stimulation (macaque R03-013). Most Gag-specific BrdU⁺ CD4⁺ T cells gated in the left-hand plot were CD95⁺ CD28⁺ (indicated by red) in the right-hand plot gated on CD3⁺ CD4⁺ lymphocytes. FITC, fluorescein isothiocyanate; PerCP, peridinin chlorophyll protein.