IgE response in schistosomiasis japonica: characterization of a cercarial allergen in comparison with purified egg allergens

Abstract

AbstractThe relationship between the cercarial allergen and two previously isolated egg allergens (J1, J2) ofSchistosoma japonicumwas examined especially in terms of the cross-reactivity between them. Semi-purified cercarial allergen (JAC) was obtained from the crude extract ofS. japonicumcercariae by gel chromatography on Sephadex G-200. The apparent molecular weight of JAC was estimated approximately as 60–100 kDa. JAC could bind to Con A-Sepharose, indicating its glycoprotein nature. Three groups of BALB/c mice were immunized with JAC, J1 or J2 using A1(OH)3as adjuvant, and the cross-reactivity of each antiserum was examined by PCA. Anti-JAC, anti-Jl or anti-J2 serum was highly specific to the corresponding antigen. When IgE-ELISA ofS. japonicumpatient sera was performed using JAC, J1 or J2 as an antigen, the correlation between anti-J1 and anti-J2 (r = 0.78) was high, whereas the correlation between anti-JAC and anti-J1 (r = 0.27) or between anti-JAC and anti-J2 (r = 0.12) was low. These results suggest that most IgE epitopes on cercarial allergen are independent from those on egg allergens inS. japonicum.