Figure 2. Antigen-specific B lineage cells and positive selection for the bone marrow plasma cell fate.

(A) PE-binding among Dump^-B220⁺ cells in naïve and immunized Aicda^cre/− Igh^96K/+ R26^LSL-YFP mice following column-based cell enrichment. (B) GC and memory cells among antigen-specific B cells gated in (A) and identified based on surface expression of CD38 and GL7. (C) Expression history of Aicda among antigen-specific naïve B cells and GC and memory B cells, gated as in (A–B). (D) IgM and IgG1 surface expression in indicated antigen-specific populations, gated as shown in (A–C). (E) Plasma cells were enriched in immunized mice from the bone marrow based on CD138 surface expression and assessed for intracellular antigen-binding and isotype expression. BMPCs were further gated as Dump⁻YFP⁺. (F) Fraction of IgG1⁺ cells among YFP⁺ cells in the antigen-specific memory, GC, and BMPC compartments of Aicda^cre/− Igh^96K/+ R26^LSL-YFP mice 40–59 days after immunization with PE. Results are combined from 3 independent experiments; each line connects the indicated cell populations from the same animal. **** p <0.0001, ** p = 0.009. Two-tailed Mann-Whitney test was used to assess significance. See also Figure S1.