Effects on anti-bovine collagen type II (BCII) antibody responses 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. Numbers of IgG anti-BCII antibody-forming spleen cells (AFCs) (a), and serum IgG (b), IgG1 (c), and IgG2a (d) anti-BCII antibody activity, 1 week after booster immunization. Each symbol represents one mouse and the bars represent the median values. Data were compared using 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.