Production of IgE antibodies against the 22 kDa tegumental membrane‐associated antigen of schistosomes is directed by the antigen itself

It has previously been reported that the predominant target of immunoglobulin E (IgE) recognition in sera from humans infected with Schistosoma japonicum in The Philippines or with S. mansoni in Kenya, is a 22 kDa tegumental membrane‐associated schistosome antigen. In the present study, we demonstrate that the 22 kDa antigen can direct the production of antigen‐specific IgE antibodies independently of schistosome infection and in the absence of any other parasite components or adjuvant. Three strains of mice were immunized using the purified, recombinant 22 kDa antigen of S. japonicum without the use of any adjuvant. Sera from all three strains of immunized mice, but not control animals, generated IgE antibodies specific for the native 22 kDa schistosome antigen in Western blots. Thus, the 22 kDa antigen itself must contain signals (presumably encoded by the primary amino acid sequence or by the secondary or tertiary structures of the molecule, or by a combination of these) which are sufficient to direct the isotype switch required for production of antigen‐specific IgE.