Clinical manifestations of arthritis in mice fed ovalbumin (OVA). Mice were fed OVA or a standard diet for 7 days. One week after the last day on the OVA diet, the mice were immunized with BCII or BCII mixed with OVA, emulsified in Freund's complete adjuvant. Three weeks later, the mice were immunized again, with the same antigen(s) emulsified in Freund's incomplete adjuvant. (a) Body weight change in mice (n = 7–9), from the day of primary immunization to 1 week after booster immunization. (b) Arthritic score 1 week after booster immunization. Bars represent mean ± standard error of the mean. The figures inside the bars in (b) show the number of arthritic mice per the total number of mice in each experimental group. (c) Progression of arthritis. Each symbol represents the mean arthritic score (n = 15–16) at the indicated day. Results from two separate experiments were calculated together in (b) and (c). Body weight changes were analyzed statistically with Student's t-test and arthritic scores, with the Mann–Whitney U test. *P < 0.05, **P < 0.01, ***P < 0.001. Ag(s), antigen(s); C, bovine collagen type II; O, ovalbumin; Od, ovalbumin-containing diet; Sd, standard diet.