CD97 monoclonal antibody (mAb) treatment protects against inflammation and erosion when treatment is started at the onset of symptoms. Mice were treated with NaCl, 0.5 mg control immunoglobulin (cIg), or 0.5 mg anti-CD97 mAb. Paws (n = 8 to 12 mice per group) were stained with haematoxylin and eosin. (a) Representative examples of joints showing intact (left) and destructed (right) cartilage derived from mice treated from day 21 on with 0.5 mg CD97 mAb or cIg, respectively. Infiltration (b,c) and erosion (d,e) scores of mice treated from day 21 (b,d) or day 35 (c,e) on. Values are mean ± standard error of the mean. *P < 0.05.