Extended Data Fig. 9: WT B cells with reduced α₄β₇ availability mimic the behavior of defective CD22-deficient B cell homing to PP.

a, WT B cells were pre-incubated with inhibitory anti-α₄β₇ Ab DATK32 (50 μg/mL) and washed extensively. DATK32-pretreated B cells were either counter-stained with Phyco-erythrin(PE)-conjugated DATK32 for flow cytometry analyses (b), or use in functional assays (c-f). b, Flow cytometry of WT + DATK32 vs. WT + Vehicle B cells stained for α_L, β₁, α₄, β₇, or α₄β₇ presented as in Fig. 1. Shown are pooled data (mean ± SEM) from n = 2 independent experiments with 4 animals per group total. c, Localization of WT, Cd22^–/–, and WT + DATK32 B cells in PLN and PP after homing assays analyzed and presented as in Fig. 6. Shown are pooled data (mean ± SEM) of n = 3 experiments with 11 mice per group total. Representative dot plots gated in live naïve B cells are also shown including the number of cells within each gate. d-f, In situ video microscopy analyses of WT B cells + DATK32 vs. Cd22^–/– B cells interactions with PP-HEVs analyzed and presented as in Fig. 6. Data represent the mean ± SEM of three independent experiments (d,f) and representative cells from all 3 experiments (e). Groups were compared using One-way ANOVA with Dunnett’s multiple comparisons test (b,c), unpaired two-tailed Student’s t-test (d,e), and paired two-tailed Student’s t-test (f). *P ≤ 0.05, **P ≤ 0.01, and ****P ≤ 0.0001. ns: not significant.