Figure 7. Long-term antibody production mediated by CD4⁺ memory T cells in mice vaccinated with aAVC-OVA.

(a) WT mice were immunized with 5 × 10⁵ aAVC-OVA and boosted with aAVC-OVA 2 weeks, 4 weeks or 8 weeks later. Serum OVA-specific antibody isotype was measured in these mice 5 days after re-challenge. (Mean ± SEM, n = 5–7) ***P < 0.001. (b) As shown in (a) but these mice were rechallenged with 5 × 10⁵ aAVC-OVA or 5 × 10⁵ DC/Gal 2 weeks later. Fourteen days after boosting, serum OVA-specific antibody isotype was measured. ***P < 0.001. (c) As in (a) these mice were boosted with aAVC-OVA 35 days after the first immunization, with or without CD4⁺ T cell depletion (d28–35). Kinetics of serum OVA-specific IgG2b was analyzed at indicated time points. (n = 8–9) **P < 0.01 (non-depleted group vs CD4⁺ T cell-depleted group at +1 week and +24 weeks) (d) OT-II transferred mice were immunized with aAVC-OVA. Four weeks after immunization, OT-II cells in spleen were analyzed for the subset. Representative plots show the percentage of CD44^hiCD62L⁺ cells after gating on CXCR5⁺PD-1^lo of transferred OT-II (CD4⁺CD45.1⁺).