Dynamic regulation of the integrin chains α4, β1, and β7 and of CXCR4 on ASCs. (A) Schematic representation of the experimental setup for comparison of NP-specific ASCs generated at different times during the immune response. (B–D) An overlay of representative flow cytometry plots showing surface expression of CXCR4 (B) and of the integrin chains α4 (C) and β1 (D) on CD138⁺NIP⁺IgG1⁺ cells from the spleens of Zfp36l1^fl/fl mice analyzed 14 d (shaded histogram) and 42 d (black line) after immunization. (E) Schematic representation of the experimental setup for pulse labeling of ASCs with EdU and detection of the newly arrived NP-specific ASCs to the BM. (F) Representative flow cytometry plots gated as in Fig. 1 D on CD138⁺NIP⁺IgG1⁺ cells and used for identification of the EdU-low and EdU-high NP-specific ASCs in the BM at day 4 following reimmunization. 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. Arrows denote the hierarchical relationship between the cell populations. (G and H) ELISPOT analysis of the BM in Zfp36l1^fl/fl CD79a^+/+ (closed circles) and Zfp36l1^fl/fl CD79a^Cre/+ (open squares) mice for ASCs secreting anti-NP₂ (high affinity) IgG1 antibody (G) and for ASCs secreting anti-NP₂₃ (high and low affinity) IgG1 antibody (H). The data in Fig. 1, B and C are presented as lines connecting the means of groups for each time point for each genotype.