(A) Total number of the indicated T cell types recovered from skin of from 5-6mo mice were calculated using AccuCheck counting beads. n = 6/group. *, p<0.05; **, p<0.01 by ANOVA. (B) FACS analysis of CD4negCD8βneg skin T cells (gated on B220-F4/80- TCRβ+) with control MR1/6-FP or MR1/5-OP-RU tetramer to identify MAIT cells in 5 mo mice. (C) Summary data of frequency of MAIT tetramer-reactive cells among total TCRβ+ cells pooled from two independent experiments, performed as in Panel B analyzing a total of 5–6 mice/group. (D) Muzzle-infiltrating cells were isolated from indicated mice, stimulated in vitro with PdBu/ionomycin, and analyzed for αβ T cell subset-specific production of IL-17A and IL-22 and for CD4+ T cell production of IL-4, and IL-13. FACS data are representative of >5 experiments. For summary data below, n = 6/group. *, p<0.05; **p<0.01, ***, p<0.001 by ANOVA or t-test (CD4-CD8β- cells). (E) Total cell number enumeration in skin draining LNs (dLNs) of 6 mo mice of indicated genotype, n = 6/group. ***, p<0.001 by Student’s t-test. (F) Muzzle draining mandibular LN (dLN) from 5 to 6 mo mice were fixed in paraformaldehyde, frozen in OCT compound, cryosectioned, and then labeled with the indicated antibodies to visualize B cell follicles (IgD+), T cell zones (CD4+), dendritic cells (CD11c+), and germinal centers (GL7+ IgD-). Images are representative of two experiments analyzing sections from at least 3 mice per experiment. (G) Summary data of T follicular helper (Tfh) cells in dLN of 6 mo LMC and Sox13-/- mice. Tfh cells were identified as CD4+FoxP3neg PD-1hi CXCR5+Bcl6+. n = 7–8/group. ***, p<0.001 by Student’s t- test. (H) Sox13-/- and 129.Tcrb-/- mice were crossed to generate double-deficient mice, and then disease progression tracked by phenotyping and muzzle inflammation assessed by H and E staining. Sox13-/-Tcrb-/- mice do not develop overt or histological signs of AD at 6 mo. Data are representative of 10–15 mice of each genotype analyzed.