Figure 2. Neutrophils are reduced in the joints of Il17ra^−/− mice and are unresponsive to direct stimulation with IL-17A.

A, Number of neutrophils in the ankle joints of WT and Il17ra^−/− mice on day 12 was determined by FACS analysis counting Ly6G⁺ cells in relation to counting beads. Data are presented as mean ± SEM (n = 3 mice per group). One of three independent experiments is shown. B, Chemotaxis of freshly isolated murine bone marrow-derived neutrophils towards 100 nM LTB₄ and IL-17A (10 and 100 ng/ml) assessed using 24-well transwell assays. Data represent numbers of migrated neutrophils (n = 3 independently performed experiments). C, Chemotaxis of freshly isolated murine bone marrow-derived neutrophils towards LTB₄ (100 nM) MIP-2 (100 nM) and IL-17A (1, 10, 100, 1000 ng/ml) as well as their corresponding chemokinesis controls assessed using 96-well ChemoTx assays. Data are presented as chemotactic index (number of cells migrating to chemoattractant/number of cell migrating to medium control). Data shown are mean ± SEM (n = 4 independently performed experiments). D, Levels of IL-17RA and IL-17RC mRNA determined by qPCR on RNA isolated from murine FLS and freshly isolated bone marrow-derived neutrophils (n = 3 independently performed experiments). Data were compared by unpaired two-tailed Student's t test, ** = p<0.01 compared to wild-type control (A), or by One-way-ANOVA with Bonferroni posttest, ** = p<0.01 compared to medium control (B) or *** = p<0.001 LTB₄ and MIP-2 each individually compared to all other groups (C).