Figure 2. Slfn5^−/− mice exhibit defective CSR.

(A) Quantification of serum immunoglobulin from Slfn5^+/+ and Slfn5^−/− mice. $n=6$ mice per genotype. Error bars indicate mean ± SD.

(B and C) Slfn5^+/+ and Slfn5^−/− splenic B cells were cultured with the indicated stimuli for 96 h and stained for surface IgG1, IgE, IgG2b, and IgG3. Representative plots of flow cytometry (FACS) are shown in (B). Quantification of CSR percentage for indicated isotypes is shown in (C). $\mathrm{n}=5$ mice per genotype. Error bars indicate mean ± SD.

(D) Slfn5^+/+ and Slfn5^−/− splenic B cells transduced with control-GFP (Ctrl^GFP) or 53bp1 shRNA-GFP (sh53bp1^GFP) were cultured in the presence of lipopolysaccharides (LPS) for 96 h. Transduced cells were stained for IgG2b and analyzed by FACS. IgG2b quantification is shown in (D). Slfn5^+/+ splenic B cell were included as a control. $\mathrm{n}=4$ mice per genotype. Error bars indicate mean ± SD.

(E and F) Slfn5^+/+ and Slfn5^−/− splenic B cells were cultured in the presence of LPS + IL-4 (E) or LPS (F) for 96 h. RAD51 accumulation at the CSR-targeted S region DNA sites was detected by ChIP-qPCR. Error bars indicate the mean ± SD of four independent experiments.

(G and H) Slfn5^+/+ and Slfn5^−/− mice were immunized with 4-hydroxy-3-nitrophenyl)acetyl-chicken γ-globulin (NP-CGG), and NP-specific serum IgM (G) and IgG1 (H) were measured at indicated times after immunization. $\mathrm{n}=6$ mice per genotype. Error bars indicate mean ± SD.

p values calculated with two-tailed unpaired t tests.