The effect of B-cell depletion with CD22/cal on the clinical scores and antibody responses in CIA. (A) Clinical arthritis scores of B6 IFN-γ-KO mice injected with CD22/cal or GG5/cal. Mice were immunized on day 0 with collagen II in CFA and given intraperitoneal injections on days 5 and 10 with CD22/cal or GG5/cal. The paws were evaluated for clinical signs of arthritis and each paw was individually scored using a 4-point scale. The results represent the mean values ± SEM for 10 mice in each experimental group. CIA was almost completely inhibited in the CD22/cal group and severe CIA was observed in the GG5/cal group (P < .001). (B) Serum IgG2b antibody levels during the course of CIA against type II collagen were measured by standard ELISA as described in “Materials and methods.” The anti-type II collagen concentrations were determined by reference to standard curves generated from 1:2 serial dilutions of a standard CIA serum to calculate the antibody content (in arbitrary units/mL). The values shown are the mean ± SEM for 10 mice in the B-cell depletion group and 15 mice in the no B-cell depletion group (10 mice injected with GG5/cal and 5 mice that had received no injections). The asterisk indicates a significant difference (P < .05) between the mean of the groups on day 15.