Fig. 5.

Epithelial RARβ regulates the development of gut homing T cells and IgA-producing B cells. (A–D) Expression of the gut homing markers α4β7 and CCR9 on T cells (CD4⁺ CD45⁺ CD3⁺) from Rarb^fl/fl and Rarb^ΔIEC littermates. (A) Representative flow cytometry plots of small intestinal T cells. Frequencies of CCR9⁺ α4β7⁺ cells in CD4⁺ CD45⁺ CD3⁺ cells from MLN (B) and small intestine (C). Total gut homing CD4⁺ T-cell numbers (CCR9⁺ α4β7⁺ CD4⁺ CD45⁺ CD3⁺) are given in D. n = 3 mice/group; data represent four independent experiments. (E) Flow cytometry of CD4⁺ (CD45⁺ CD3⁺) T cells from the small intestines of Rarb^fl/fl and Rarb^ΔIEC littermates. CD4⁺ (CD45⁺ CD3⁺) T-cell frequencies are quantified in F and total small intestinal CD4⁺ T-cell numbers (CD4⁺ CD45⁺ CD3⁺) are given in G. n = 3 mice per group; data represent four independent experiments. (H) Flow cytometry analysis of IgA⁺ B220⁺ (CD45⁺ CD19⁺) B cells from Rarb^fl/fl and Rarb^ΔIEC littermates. IgA⁺ B220⁺ cell frequencies in CD45⁺ CD19⁺ B cells are quantified in I, and total numbers of small intestinal IgA⁺ B cells are shown in J. n = 3 mice per group; data represent four independent experiments. (K) Quantification of fecal IgA by ELISA. n = 4 mice/group; data represent two independent experiments. Means ± SEM are plotted. *P < 0.05; **P < 0.01 as determined by Student’s t test. sm. int., small intestine. MLN, mesenteric lymph nodes.