Differential induction of regulatory T cells and TGFβ secretion during immunization. The presence of regulatory T cells (CD4⁺/CD25^hi/FoxP3⁺) was assayed from isolated splenocytes from all groups (n = 4) via flow cytometry (A). Analysis of flow cytometry shows differences in Treg populations, whereas analysis of cytokine secretion from these cells shows differences in TGFβ release (B). P values reflect comparisons between mice vaccinated with Gag4Y alone with mice vaccinated with Gag4Y plus IL-12 or IL-28B.