Cxcr5−/− mice exhibit disordered LTi-like cell organization. (A) Crypt-level CD90+ (THY1+) aggregates quantified by whole-mount staining of SIs (n = 3). (B) RORγt+ aggregates in proximal and distal sections of Cxcr5−/−Rag1−/− and Rag1−/− SIs. (C) CD4 and RORγt staining in a villus lymphoid aggregate in a Cxcr5−/−Rag1−/− proximal SI. (D) Frequency of LTi-like cells in the proximal and distal SI (n = 6). (E) Frequency of IL-22– and IL-17A–producing, LTi-like cells isolated from the proximal (Top) and distal (Bottom) intestine and stimulated with 1 ng/mL IL-23 (n = 6). (F) Fold change of cytokine production from data shown in E. Bar graphs show mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 (unpaired Student’s t test). ns, not significant. Data are pooled from two independent experiments (D–F).