Accumulation of Ag-specific ASCs in the BM but not their generation in the spleen is impaired after both primary immunization and reimmunization in Zfp36l1^fl/fl CD79a^Cre/+ mice. (A–C) ELISPOT analysis of NP-specific ASCs in Zfp36l1^fl/fl CD79a^+/+ (closed circles) and Zfp36l1^fl/fl CD79a^Cre/+ (open squares) mice. Enumeration of ASCs secreting anti-NP₂ (high affinity) IgG1 antibody in the spleen (A) and BM (B) and of ASCs secreting anti-NP₂₃ (high and low affinity) IgG1 antibody in the BM (C). For all plots in all panels, each symbol displays data from an individual mouse, lines represent means, and data are representative of two independent experiments for day 14 (n ≥ 4; two-way ANOVA on logarithmically transformed data; the P values shown are for the main genotype effect). (D) Representative flow cytometry plots showing intracellular staining with IgG1 antibody and NIP-BSA-biotin to identify NP-specific ASCs in the spleen (three top plots) and the BM (three bottom plots); intracellular NIP^hi, IgG1^hi cells (middle plots) were identified in the population of all CD138⁺CD267⁺ cells (left plots, gated on eFluor780⁻CD3⁻IgD⁻ cells), and their absence was confirmed in a nonimmunized mouse (right plots). (E and F) Quantification of CD138⁺NIP⁺IgG1⁺ cells in Zfp36l1^fl/fl CD79a^+/+ (closed circles) and Zfp36l1^fl/fl CD79a^Cre/+ (open squares) mice at days 5 and 6 after reimmunization in the spleen (E) and the BM (F) normalized to the numbers of all eFluor780⁻ cells in the sample (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.