Fig. 4

Commensal microbiota drive potentiated Th17 response and spontaneous arthritis in IL1rn ^−/− mice. a–d Frequency and numbers of IFNγ-producing (a, b) and IL-17-producing (c, d) CD3⁺CD4⁺ SI-LP cells. Data are pooled from three independent experiments. e Arthritis severity scores of conventional (CV, n = 12) and germ-free (GF, n = 11) IL1rn ^−/− mice of a representative experiment. Scale 0–2 for each hind paw. Mean + SEM is shown. f–h Production of IFNγ, IL-17, and IL-4 upon ex vivo stimulation of the spleen and lymph node cells from CV and GF mice with PMA and ionomycin for 6 h, as measured by Luminex assay. n = 3 mice per group of each stimulated in triplicate. n.s. not significant, **P ≤ 0.01 and ***P ≤ 0.001, by Mann-Whitney U test. See Additional file 1: Figure S3 for gating strategy