Figure 4. LRF is required for α4β7 expression on IELp.

(a) Histogram shows the expression of S1pr1 on IELp from Ctrl (black solid line) and LRF KO (black dashed line) mice. Gray-shaded histogram (Bkgd) shows background of PE fluorochrome signal in IELp from Ctrl mice for which the primary S1pr1 antibody was omitted from the staining mix. Data are from one experiment representative of two, each with one mouse per genotype.

(b-d) Histogram overlays (left) show staining of Ctrl and LRF KO IELp with antibodies specific for the α4β7 integrin dimer (b), or for its α4 (c) or β7 subunits (d). Gray shaded histogram shows the same staining on wild-type CD4⁺CD8⁺ thymocytes. Graphs on the right show the percentage of cells gated in histograms (left) and indicated protein expression (mean fluorescence intensity, MFI, right); MFI is computed on cells expressing each protein (left plot bracket) and expressed relative to that in IELp from wild type C57BL/6 mice, set at 100 in each experiment. Data pooled from two independent experiments with a total of 4 mice per group. Each symbol represents one mouse.

(e) Histograms show expression of α4β7 dimers in indicated IELp from bone marrow chimera analyzed in Fig. 1e. Graph (bottom) shows the percentage of α4β7⁺ cells among IELp. Data pooled from two independent experiments with a total of 6 mice per group. Each symbol represents one mouse.

Error bars indicate standard error of the mean (SEM). P values are from two-tailed unpaired t-test (b, d and e) or two-way ANOVA (c).