Figure 3. Expression of a 3′RR-deleted allele in splenic B cells.

(A) Flow cytometry analysis of IgM^a and IgM^b in spleen of heterozygous a^Δ3′RR/b^wt, a^wt/b^wt and a^ΔEμMARs/b^wt mice. One representative experiment out of ten is shown for a^Δ3′RR/b^wt and a^wt/b^wt mice. One representative experiment out of four is shown for a^ΔEμMARs/b^wt mice. Cells were gated on B220⁺ cells. (B) Percentages (left part) and numbers (right part) of B220⁺ splenic B cells expressing the a or b allele in a^Δ3′RR/b^wt, a^wt/b^wt and a^ΔEμMARs/b^wt mice. Mean ± SEM of ten a^Δ3′RR/b^wt mice, ten a^wt/b^wt and four a^ΔEμMARs/b^wt mice. Millions of splenic B cells are reported. The significance is for IgM^a cells in the right part. *p < 0.05, **p < 0.01, **p < 0.01 (Mann-Whitney U-test). (C) Flow cytometry analysis of follicular (FO) B cells (B220⁺CD21^lowCD23^high) and marginal zone (MZ) B cells (B220⁺CD21^highCD23^low) in a^Δ3′RR/b^wt and a^wt/b^wt mice. One representative experiment out of ten is shown. Cells were gated on B220⁺ cells. (D) Percentages and numbers (in millions) of TR (AA4.1⁺), FO and MZ B cells in a^Δ3′RR/b^wt and a^wt/b^wt mice. Mean ± SEM of ten mice. Million numbers of cells are reported. The significance is for MZ IgM^a cells in the right part. **p < 0.01 (Mann-Whitney U-test). (E) IgM^a and IgM^b densities on TR, FO and MZ B cells in a^Δ3′RR/b^wt and a^wt/b^wt mice. Mean ± SEM of ten mice. *p < 0.05, **p < 0.01 (Mann-Whitney U-test). (F) μ transcription in sorted TR, FO and MZ B cells of a^Δ3′RR/b^wt and a^wt/b^wt mice. Mean ± SEM of 6 mice. Values were normalized to GAPDH transcripts. *p < 0.05, **p < 0.01 (Mann-Whitney U-test).