Comparison of IFN-γ+, IL-17+, IL-4 + or IL-22+ cells among aged and young CXCR5 + CD4 + Tfh. PBMCs were prepared, stimulated with PMA and inomycin for 4–6 hours, and intracellular staining were done. FACS data were analyzed: lymphocytes were first gated and then CD4 + CXCR5+ or CD4 + CXCR5- cells were gated and cytokines such as IFN-γ, IL-17, IL-4 and IL-22 were analyzed. Statistical data of frequencies of IFN-γ + (A), IL-17 + (B), IL-4 + (C) and IL-22 + (D) among CD4 + CXCR5 + Tfh or CD4 + CXCR5- cells were shown. *: p < 0.05, n.s: no significant difference. All data were expressed with line at mean with SEM.