FIG. 4.

B cells from IFN-γ-deficient and IL-10-deficient mice fail to class switch to IgG2b. Wild-type (WT), IFN-γ^−/− (a), and IL-10^−/− (b) mice (six per group) were immunized with MSP1₁₉, MSP2A, or Con-C, and median midpoint titers of IgG1 and IgG2b were measured by ELISA 2 weeks after the final immunization. The statistical significance of differences between wild-type and cytokine-deficient mice was determined using nonparametric (Wilcoxon signed rank) tests and is indicated. *, P < 0.05; **, P < 0.005.