Denaturation of ovalbumin abrogates oral induction of airway hyperreactivity and IgG1, IgG2 antibody responses in guinea pigs

Background: The effects of denaturation of ovalbumin (OVA) on the induction of oral sensitization in guinea pigs were examined. Methods: Guinea pig an tibody and airway responses were assessed after 10 feedings of chemically o r heat-denatured OVA or egg white (EW), Results: Their specific IgG, IgG 1 and IgG2 antibody responses were orally sensitized by OVA or Ew, but not by chemically or heat-denatured OVA or Ew. When further exposed to 0. l% OVA or conalbumin aerosol, those fed OVA or EW, but not denatured OVA or EW: ha d increased pulmonary resistance and decreased tidal volume. On the other h and, in those fed denatured OVA, boiled EW or saline only, a second sensiti zation with 1% OVA aerosol generated antibody responses and airway hyperrea ctivity. Using a sandwich ELISA, guinea pig serum OVA was detected after fe eding EW, but not chemically denatured or boiled EW. Conclusions: It is lik ely that guinea pig gut absorption of OVA may result in oral sensitization. Chemical or heat denaturation of proteins may minimize their intestinal up take and thus abrogates the induction of oral sensitization in guinea pigs.