Effects on ovalbumin (OVA)-specific immune responses in mice fed 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 OVA or OVA mixed with bovine collagen type II (BCII) 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) IgG anti-OVA antibody activity in serum 1 week after the booster immunization. Each circular symbol represents one mouse and the bars represent the median values. Data were compared using the Mann–Whitney U test. In vitro proliferation (b) and secretion of IFN-γ (c), IL-4 (d), and IL-10 (e) by splenocytes after OVA restimulation 1 week after the booster immunization. The proliferation results are presented as proliferation indexes (mean counts per minute [cpm] in triplicate cultures stimulated with OVA/mean cpm in triplicate control cultures). Bars represent mean ± standard error of the mean (n = 7–9). *P < 0.05, **P < 0.01, ***P < 0.001 (Student's t-test). Ag(s), antigen(s); C, bovine collagen type II; O, ovalbumin; Od, ovalbumin-containing diet; Sd, standard diet.