Nod2−/− Jax mice have normal recirculating B cell, marginal zone B cell, and B1a cell compartments, and display normal proliferation and class switch recombination (CSR) in vitro. (A) Number of of total live cells and B220+ CD19+ B cells in the spleen. (B) Percentage of bone marrow recirculating B cells (B220high IgM+). (C) Percentages of marginal zone (CD21 high CD23 low) and follicular (CD21 low CD23 high) B cells in the spleen. Population are gated on B220+ CD19+ AA4.1- mature B cells. (D) Percentages of B1a cells (B220 low, CD19+ CD5+) from peritoneal lavage and spleen. (E) Representative plots and percentages of proliferating CD138+ plasma cells after in vitro stimulation of mature B cells with LPS for 4 days. (F) Representative plots and percentages of proliferating IgG1+ B cells after in vitro stimulation of mature B cells with Il-4 and anti-CD40 for 4 days. For A–D, data is representative of three independent experiments from a total of WT (n = 3), Nod2−/− (n = 5), and Nod2−/− Jax (n = 6) mice. For E–F, data is representative of two independent experiments from a total of WT (n = 7), Nod2−/− (n = 3), and Nod2−/− Jax (n = 4) mice. ns p > 0.05 and **p ≤ 0.01 by two-tailed Mann-Whitney.