Reduced number of Ag-specific ASCs in the BM of Zfp36l1^fl/fl CD79a^Cre/+ mice can be fully accounted for by defective migration of the newly generated ASCs to the BM. (A) Schematic representation of the experimental setup for detection of the newly arrived NP-specific ASCs to the BM. (B) Representative flow cytometry plots gated as in Fig. 1 D on CD138⁺NIP⁺IgG1⁺ cells and used for detection of newly generated (BrdU-high) NP-specific ASCs and the established (BrdU-low) NP-specific ASCs in the spleen at day 4 following reimmunization with NP-KLH in alum (two top plots) and in the BM (two bottom plots). (C and E) Frequency of CD138⁺NIP⁺IgG1⁺ cells of Zfp36l1^fl/fl CD79a^+/+ (closed circles) and Zfp36l1^fl/fl CD79a^Cre/+ (open squares) or Zfp36l1^fl/fl Cd23-Cre⁺ (open squares) mice at day 4 after reimmunization; the numbers of all CD138⁺NIP⁺IgG1⁺ cells in the spleen (C) and BM (E) are normalized to the numbers of all eFluor780⁻ cells in the sample. (D, F, and G) As above, but the populations of CD138⁺NIP⁺IgG1⁺ cells are split on the basis of BrdU staining into the BrdU-high NP-specific ASCs (D and F) and the BrdU-low NP-specific ASCs (G) and quantified in the spleen (D) and the BM (F and G). (H) The ratio of the number of BrdU-low NP-specific ASCs to the number of BrdU-high NP-specific ASCs in the BM. For all plots in all panels, each symbol represents data from an individual mouse, and lines represent means. For each Cre-expressing line, data are representative of two independent experiments (n ≥ 4; two-way ANOVA; the P values shown are for the main genotype effect). For all flow cytometry plots, the numbers next to the enclosed areas (gates) represent percentages of the cells falling into the gate, and the number in the bottom right corner shows the number of cells in the plot.