Figure 2.

OVA- and CTB–specific CD4⁺ T cell proliferative responses. Groups of C57BL/6 mice were immunized subcutaneously with 100 μg of OVA alone or together with 10 μg of rCT-B, 1 μg of nCT, or 10 μg of mCTs, S61F, or E112K, on days 0 and 14. Purified splenic CD4⁺ T cells were cultured at a density of 2 × 10⁶ cells/ml in the presence of 1 mg/ml of OVA or 10⁷ CT-B–coated beads/ml, T cell–depleted, irradiated splenic feeder cells (2.5 × 10⁶ cells/ml) and IL-2 (10 U/ml) in complete medium. Bars represent the mean stimulation index ± SEM in each group. Each group contained 10 mice and are representative of three separate experiments.