Isolation of Two Immunogenically Different Allergens from Schistosoma japonicum Eggs

Abstract

Two allergenic components, termed J1 and J2, were isolated from a soluble egg antigen preparation (SEA) of Schistosoma japonicum by anion-exchange chromatography on DE52 and gel chromatography on Sephacryl S-200. The apparent molecular weights of J1 and J2 were 260,000 and 46,000, respectively, by gel chromatography on Sephadex G-150. By SDS-polyacrylamide gel electrophoresis, both J1 and J2 showed apparent homogenicity and their estimated molecular weights were 135,000 and 45,000, respectively. The isoelectric point of J1 (pI 4.9) was similar to that of J2 (pI 4.8). Both J1 and J2 bound to Con A-Sepharose 4B, indicating their glycoprotein nature. The amino acid compositions of J1 and J2 have some similarities. However, phenylalanine and leucine, which contain large hydrophobic groups, were dominant in J1, whereas serine and threonine, which contain a hydroxyl group, were dominant in J2. J1 was sensitive to heating or pronase treatment, whereas J2 was rather stable to these treatments. Both J1 and J2 were sensitive to 0.1 M periodate treatment. When mice were immunized with either J1 or J2 with Al(OH)₃ as an adjuvant, anti-J1 or anti-J2 IgE antibody was highly specific to the respective antigens. Since S.japonicum-infected mouse serum has high PCA titer to J1 and J2, these two components are the major allergens of S. japonicum eggs.