Figure 4. Reduced Ig expression in 53BP1‐, SHLD2‐, and SHLD3‐deficient CH12 cells is permanent and dependent on CSR.

• A
  WT and two independent clones each of 53bp1 ^−/−, Shld2 ^−/−/−, and Shld3 ^−/− CH12 cells were stimulated with CIT and analyzed by flow cytometry for IgM and IgA expression. The Ig^lo population was reduced after 7 days in culture. Values are mean ± SD from 3 biological replicates; *P ≤ 0.05, **P ≤ 0.01, ****P ≤ 0.0001, two‐way ANOVA with post hoc Dunnett's test.
• B
  WT and two independent clones each of 53bp1 ^−/−, Shld2 ^−/−/−, and Shld3 ^−/− CH12 clones were stimulated with CIT for 3 days. The IgM⁺, IgA⁺, and Ig^lo populations were sorted and reanalyzed for expression of IgM and IgA 5 days post‐sort as well as 12 days post‐sort (see Fig EV4B). Shown on bar graphs are sorted IgM⁺, IgA⁺, and Ig^lo populations (each column, 1 technical replicate) from WT and mutant CH12 clones, and the percent of cells expressing IgM, IgA, or low for both isotypes (Ig^lo) after 5 days of culture post‐sort. A representative flow plot of 53bp1 ^−/− CH12 3 days post‐CIT treatment is shown.