[Induction of oral tolerance to experimental allergic conjunctivitis in rats]

Immunological tolerance can be induced by the oral administration of antigen. We induced oral tolerance rats to experimental allergic conjunctivitis by ovalbumin and investigated the suppression of inflammation. In groups which had started eating antigen both before and after the immunization, the serum anti-ovalbumin IgE level measured by passive cutaneous anaphylaxis reaction was significantly lower than in a group that had not been fed antigen. The intensity of experimental allergic conjunctivitis in the group which had started eating antigen before immunization, was significantly suppressed in regard to the leakage of Evans Blue from conjunctival vessels 30 minutes after the challenge and the neutrophil infiltration 6 hours after. The dye leakage of the group which had started feeding after immunization was also significantly suppressed. There was a positive correlation between the serum IgE level and the leakage of Evans Blue (r = 0.90, p < 0.001). These results suggest that the suppression of antigen-specific IgE antibody production caused by oral tolerance affected the decrease of local inflammation on the conjunctiva.