IL-23 has a critical role in the progression of antigen-induced arthritis. WT and IL-23p19KO mice were immunized with mBSA/CFA and one week later mono-arthritis was induced by injecting mBSA directly into the knee joints. A. Arthritis score was determined macroscopically at different time points. Mean values and SEM are given for 8 to 31 mice per group. Data are obtained from three separate experiments. * P < 0.001, WT vs IL-23p19KO. B, Histological analyses of joint inflammation and, C, bone erosion after H&E staining. B and C, Mean values and SEM are given from two separate experiments with a total of 20 knee joints per group. D-F. Cytokine levels in synovial washouts taken at days 1, 2 and 7. G and H. IL-17A and IFN-γ levels in synovial washouts taken at day 1. Mean values and SEM are given for 5 to 10 washouts obtained from two separate experiments.