Panel A shows schematic diagram of Ighm exon 4 and adjacent region organization in WT, M-only, and mM-only mice constructs. Panel B shows scatter plot graph of pro-, pre-, immature, and mature B cells in bone marrow; vertical axis number of cells in millions and horizontal axis developmental stages. Panel C shows scatter plot graph of splenic B cell subsets; vertical axis number of cells in millions and horizontal axis subsets including transitional, marginal zone, and follicular populations. Panel D shows scatter plot of splenic marginal zone B cell percentage; vertical axis percentage of cells and horizontal axis mouse genotypes. Panel E shows scatter plot graph of live B cell numbers in spleen, mesenteric lymph node, and Peyers patches; vertical axis number of cells and horizontal axis tissues. Panel F shows scatter plot graph of plasma cells in bone marrow; vertical axis number of cells in thousands and horizontal axis mouse genotypes. Panel G shows bar graph of serum immunoglobulin levels measured by ELISA; vertical axis immunoglobulin concentration and horizontal axis antibody isotypes. Panel H shows two bar graphs of relative gene usage frequencies in follicular B cells; vertical axis frequency percentage and horizontal axis immunoglobulin heavy and light chain variable genes.
B cell development in M-only and mM-only mice. (A) Schematic shows structure of Ighm exon 4 and adjacent region in WT, M-only, and mM-only mice. (B) Number of pro-, pre-, immature, and mature B cells in the bone marrow on one leg by flow cytometry. Gating as in Fig. S1 A. (C) Number of the splenic B cell subsets by flow cytometry. Gating as in Fig. S1 B. (D) Percentage of splenic marginal zone B cells. Gating in Fig. S1 B. (E) Number of live B cells in spleen, mLN, and PP by flow cytometry. Gating in Fig. S1, B–D. (F) Number of PCs in the bone marrow of one leg by flow cytometry. (G) ELISA quantification of total IgM, IgG3, IgG1, IgG2b, IgG2c, and IgA in the serum of WT, M-only, and mM-only mice. (H) Bar graph depicting the relative abundance of Ighv (left panel) and Igkv (right panel) gene usage in follicular B cells. Top 10 most frequent genes ranked by the mean frequency in mM-only mice are shown. Data were pooled from two independent experiments. Each dot or circle represents a mouse. P values of nonparametric one-way ANOVA with Tukey’s Honest Significant Difference test are shown. All experiments were performed at least twice. *P < 0.05, **P < 0.01, ***P < 0.001. Bars indicate the mean ± SD. PP, Peyer’s patches, LOD, Limit of Detection.