Figure 5D. HA@PPCDQ induces higher frequency of HA-specific GC Tfh (CD25+OX40+) cells at 1 weeks after boost vaccination.

C57BL/6 mice (n = 5) were immunized with PPCDQ nanovaccines or soluble protein, respectively. Splenocytes were isolated at 7 days post-boost and stimulated with His-tagged HA protein for 24 h. Then, samples were incubated with cocktail surface markers for FCM analysis.