Effects of diphenyl dimethyl dicarboxylate on oral tolerance to ovalbumin in mice

The effects of diphenyl dimethyl dicarboxylate (PMC) on oral tolerance to ovalbumin (OVA) were investigated in C3H/HeN and BALB/c mice. Mice orally received 20 mg OVA or 20% starch solution were immunized 7 days later with an i.p. injection of 0.1 mg OVA in complete Freund's adjuvant (CFA). The effects of oral OVA and PMC on antibody production were assessed by ELISA of immunoglobulin (Ig) subclass level in serum collected 7 days after immunization. Oral tolerance was obtained enough on day 7 after immunization and was more effective in C3H strain than in BALB strain, associated with decreases of anti-OVA IgG, IgG1, IgG2a and IgM levels. After oral OVA, oral administration of PMC for 6 days significantly elevated anti-OVA IgG, IgG1, IgG2a and IgM levels in mice hyposensitized by the oral OVA. These findings indicate that PMC is an useful modulator of oral tolerance to OVA in these two strains.