B cells play a role in amplifying antigen-specific CD4⁺ T-cell responses toward DEC-205–targeted antigen in vivo. (A) C57BL/6 mice or the B-cell deficient JHT mice were immunized with 5 μg of isotype control fusion mAb with 50 μg polyIC (IgG-p24 + polyIC), or αDEC-205 mAb conjugated with HIV gag p24 (αDEC-p24) without or with 50 μg polyIC (αDEC-p24 + polyIC) as adjuvant, and boosted 1 month later. The mice were killed a week after boost, bulk splenocytes were harvested, stimulated with either gag p24 peptides or gag p17 peptide mix, IFNγ production was evaluated by intracellular cytokine staining in the CD3⁺CD4⁺ gated cells. (B) As in panel A, mean ± SD from 2 independent experiments with 3 mice per group is shown. P value was calculated with 2-tailed Student t test.