The present study extended our understanding of the primary structure of isoforms of Cyn d 1.

The effect of chemical denaturation of ovalbumin (OVA) on the induction of oral tolerance of reaginic antibody responses was studied. Both urea-denatured OVA (UD-OVA) and carboxymethylated UD-OVA (CM-OVA) were purified by centrifugation. When compared with OVA and UD-OVA, CM-OVA had the least sensitizing capacity and allergenicity in IgE responses to OVA. BALB/c IgE, IgG1 and IgG antibody responses were suppressed by OVA, but not by UD-OVA or CM-OVA, fed prior to sensitization with OVA, UD-OVA, or CM-OVA in alum, respectively. The priming effect of specific IgG and IgG1 antibody responses was induced by CM-OVA fed prior to sensitization with OVA or CM-OVA. The proliferation of BALB/c spleen cells and their secretion of T helper type 2 (Th2) cytokines interleukin-4 (IL-4) and IL-5 were also orally tolerized by OVA, but not by denatured OVA. Although denatured OVA is hypoallergenic, the present result indicates that denaturation of a soluble protein prevents the induction of oral tolerance of Th2 responses.