Figure 7.

Increased IgG2b production in Rac1^BRac2^−/− B cells. (A) Ig class switching to IgG1, IgG2a, IgE, and IgA. Mice were sacrificed on day 3 after the last tamoxifen-injection and purified B cells were cultured with different stimuli. For IgG1 and IgE, B cells were stimulated with anti-CD40 + IL-4, for IgG2a with lipopolysaccharide (LPS) and IFNγ, and for IgA with LPS + IL-4 + IL-5 + TGFβ for 4 days. n = 2–8 mice per group, where each dot represents one mouse. (B) Ig class switching to IgG2b and IgG3. B cells were stimulated with LPS for 4 days. n = 4–9 mice per group, where each dot represents one mouse. (C) Ratio of percentages of IgG2b divided by that of IgG3. Each dot represents one mouse. (D) Total number of IgG2b⁺ or IgG3⁺ cells per milliliter of culture after stimulation for 4 days with LPS. Values represent mean of triplicates, bars represent SD. The experiment was repeated once with similar results. (E) Germline (GL) γ2b transcripts in wild-type (WT) and in Rac1^BRac2^−/− B cells after stimulation for 2 days with LPS. The GLγ2b expression was normalized to that of GAPDH. WT was set to 1. Each dot represents one mouse. Statistical analysis was performed using unpaired two-tailed t-test (A–C), Student’s non-paired t-test (D), and non-parametric Kolmogorov–Smirnov t-test (E). *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.