Figure 3.

Soluble leishmanial antigen–CpG–DCs vaccination reduces the suppressive properties of the CD4⁺CD25⁺Foxp3⁺ T cells in L. donovani-infected mice. (A) CD4⁺CD25⁺ T regulatory cells and CD4⁺CD25⁻ T cells were purified from spleen of differently treated mice (Materials and Methods) after 4 weeks post-infection. CD4⁺CD25⁻ T cells (5 × 10⁵) and T-depleted, mitomycin C-treated syngeneic APCs (5 × 10⁵) were stimulated with SLA (10 μg/ml) and co-cultured in the presence of splenic CD4⁺CD25⁺ T cells(1:1 ratio) from differently treated sets for 4 days. Proliferation was determined by an 18 h (³H) thymidine incorporation assay. Data are presented as counts per minute (CPM) × 10³. The supernatants were collected at 24 h for IL-2 (B) or at 72 h for IFN-γ (C) following stimulation with SLA (10 μg/ml) and levels of cytokines were determined by ELISA. The error bars represent mean ± SD of triplicate cultures. The experiments were performed three times, of which one set of representative data is shown (**P < 0.001 and *P < 0.05).