Oral immunotherapy may induce T cell anergy.

Recently, the induction of T cell anergy has been considered as a sophisticated form of immunotherapy. However, the multiplicity of T cell allergen epitopes discourages the practical use of this method. Since orally administered antigen proteins are digested to peptides and absorbed into the circulation, oral administration of antigen might be an apparently primitive but practically very useful therapeutic approach. Freeze-dried body extract of Dermatophagoides farinae mite in tight capsules was orally administered at 0.5-3 mg/day to 17 adult male mite-sensitive asthmatic patients for 12 weeks. Marked and moderate improvement of clinical symptoms judged by symptom scores and peak expiratory flow was observed in 47% (8/17) of the patients. Bronchial provocation tests carried out before and after oral immunotherapy showed a statistically significant improvement especially in the late asthmatic response. The peripheral blood eosinophil count decreased significantly after oral immunotherapy. Interleukin-5 spontaneously produced by patient peripheral mononuclear cells decreased significantly (p < 0.05) after the oral immunotherapy. These results suggest that T cell anergy might be achieved by oral immunotherapy.