Treatment with anti-JAM-C antibody decreases neutrophil infiltration into the joints during antigen-induced arthritis. Infiltration of neutrophils (a), lymphocytes (b), and macrophages (c) into the synovium was detected by immunohistochemistry using anti-MPO, anti-CD3, and anti-MAC-2 antibodies, respectively. The left panels show representative knee joint sections of control and anti-JAM-C antibody-treated mice. Original magnification × 400 (scale bar = 25 μm). In the right panels, leukocyte infiltration per field was evaluated by semi-quantitative scoring for anti-JAM-C antibody-treated (n = 6, black columns) and isotype-matched control antibody-treated (n = 5, open columns) mice. There was a significant decrease in synovial neutrophil infiltration in anti-JAM-C antibody-treated mice as compared to isotype-matched antibody-treated controls. *p < 0.05 versus control mice, as assessed by analysis of variance. Ab, antibody; JAM-C, junctional adhesion molecule-C.