Effects of oral tolerance in allergen-induced airway responses

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Oral administration of soluble antigen before immunization induces peripheral tolerance and is effective in suppressing animal models of autoimmune diseases. However, few studies have focused on effects on Th-2 type diseases. Mice were sensitized to ovalbumin(OVA) and subsequently challenged with OVA via the airways, eliciting airway hyperresponsiveness(AHR) and airway inflammation. The feeding effects of OVA at different phases of the immune response were evaluated. Mice exposed to both multiple high dose feeding and multiple low dose feeding before sensitization with OVA failed to develop AHR or airway inflammation. High dose feeding of OVA also abrogated AHR and partially suppressed airway inflammation when initiated after sensitization with OVA, but prior to challenge ; low dose feeding partially suppressed AHR but did not affect the development of airway inflammation. High dose but not low dose feeding was effective on AHR when initiated even after challenge with OVA. These data indicate that the dose and phase of the response may be critical in dictating the effect of inducing oral tolerance on allergen-induced AHR and airway inflammation