Klf2 is required for PC egress from the SPL to blood. (A) GSEA showing the enrichment for KLF2 target genes (left) or Klf2 mRNA expression (right), in SPL integrin β7^hi (n = 4) or integrin β7^lo PCs (n = 5). (B) Experimental setup to analyze the development of PCs from B1–8^hi R26-creERT2 Klf2^fl/fl B cells (for C–E). Klf2 in donor B cells was deleted by tamoxifen treatment. (C)Klf2 mRNA expression in SPL PCs derived from R26-creERT2 Klf2^+/+ or Klf2^fl/fl B cells after tamoxifen treatment (n = 3). (D) Representative FCM plots showing donor-derived PCs (CD45.1⁺) among CD138⁺ PCs (left), or the number of CD45.1⁺ PCs (right), in SPL, blood, or BM (n = 4). (E) Representative FCM plots showing expression of integrin β7 and CD11b (upper) or frequency of integrin β7^hi and CD11b^hi (lower) in R26-creERT2 Klf2^+/+ or Klf2^fl/fl SPL PCs (n = 5). (F) Experimental design of adoptive co-transfer of B1–8^hi R26-creERT2 Klf2^+/+ and Klf2^fl/+ B cells. (G) Representative FCM plots showing Klf2^+/+ (CD45.1/1) or Klf2^fl/+ (CD45.1/2) (left), or the frequency of Klf2^fl/+ PCs (right) among CD45.1⁺ SPL, blood, or BM PCs (n = 4). Data in A, C–E, and G are representative of two independent experiments (n = 3 for A, n = 5 for C, n = 3 or 4 for D and E, and n = 3 for G, in the second experiment). Data were analyzed by two-tailed unpaired Student’s t test (A and C–E) or one-way ANOVA followed by Tukey’s multiple comparison test (G). ns., not significant; *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001. PCs, plasma cells; SPL, spleen; BM, bone marrow.