CHEMICAL DENATURATION OF OVALBUMIN ABROGATES THE INDUCTION OF ORAL TOLERANCE OF MOUSE REAGINIC ANTIBODY-RESPONSES

The effect of chemical denaturation of ovalbumin (OVA) on the inductio n of oral tolerance of reaginic antibody responses was studied. Both u rea-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 speci fic 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 interleuk in-4 (IL-4) and IL-5 were also orally tolerized by OVA, but not by den atured OVA. Although denatured OVA is hypoallergenic, the present resu lt indicates that denaturation of a soluble protein prevents the induc tion of oral tolerance of Th2 responses.