FIG 2.

Antibiotics and IL-15 inhibition reduce synovitis, bone erosions, and osteoclast numbers in the joint but do not influence cartilage destruction during S. aureus-induced arthritis. (A to E) Effects of adding aIL-15ab to antibiotics on joint inflammation, bone erosions, and cartilage destruction, on the number of osteoclasts, and on the proportion of granulocytes in the synovium. Shown are representative stained sections (hematoxylin and eosin, Van Gieson, Safranin O, and cathepsin K) of inflamed joints on day 12 postinfection. The severity of joint inflammation, or synovitis, and joint destruction was evaluated by making a histological scoring of synovitis (A), bone erosions (B), and proteoglycan loss in the articular cartilage (C) and by counting the number of osteoclasts (arrows) in the epiphyseal part of femur and tibia after cathepsin K staining (D). (E) Proportion of granulocytes in the synovium. Data are representative of three separate experiments (n = 10 mice/treatment group). The horizontal bars in panels A to E show median values; the whiskers represent minimum to maximum ranges. Statistical differences were calculated using a Mann-Whitney U test. **, P < 0.01 compared to the control group. Scale bars, 100 μm. Abbreviations: A, antibiotics; ctrl ab, control antibodies; aIL-15ab, anti-IL-15 antibodies.