Reactivity of two major allergens isolated from Schistosoma japonicum eggs against IgE and IgG antibodies in human serum.

Antigenicity and specificity of two major allergens termed J1 and J2, both of which had been purified from soluble egg antigen (SEA) preparation of Schistosoma japonicum, were examined against serum from schistosomiasis japonica patients. By using enzyme-linked immunosorbent assay, specific IgE or IgG levels to J1 or J2 in the patients' sera correlated well with those to crude SEA, indicating that J1 and J2 are the major antigens in SEA binding human IgE and IgG antibodies. Binding inhibition studies using 125I-J1 and 125I-J2 clearly showed that cross-reactivity was not present between J1 and J2 in terms of their capacity to bind IgG or IgE antibody. When antibody levels of an individual patient to these two purified antigens were compared, a high degree of correlation was observed between them, regardless of the class of antibody. However, specific IgE antibody levels of individual serum to J1 or J2 were not correlated with IgG antibody levels to the respective antigen.