Fig. 2.

Normal IgM-expressing naïve B-cell subsets require the 3′RR distal module. B-lineage cell subsets in heterozygous models: wt^a/^b, 3′PAL^Δa/^wtb, hs3b-4^Δa/^wtb, and 3′RR^Δa/^wtb. Bone marrow NF/immature and mature recirculating (MR) B cells; spleen transitional, MZ, and FO B cells; peritoneal cavity B1a and B1b subsets were analyzed by flow cytometry as described in Fig. S2. Top histograms display percentages of IgM^a (white) or IgM^b (black) expressing cells; gray histograms below reported the corresponding ratio. Bottom histograms give intracellular IgM^a or IgM^b allotype mean fluorescence (MF), gray histograms below report the corresponding MF ratio. Cell numbers were collected from five to seven animals of each genotype. Significant differences were indicated by P values: *P < 0.05, **P < 0.01, ***P < 0.001 according to the Mann–Whitney u test.