Characterization of the carbohydrates of Schistosoma japonicum adult worm, egg and cercaria by analysis of lectin binding and antibody reaction.

Binding of the FITC-labeled lectins, Con A, SBA, WGA, DBA, UEA 1 and RCA 120 were examined on various kinds of cross-sections of S. japonicum adult worms and eggs, and on cercaria specimens. The specificity of the lectin bindings was examined by inhibition test with specific carbohydrates or with unlabeled lectins. Furthermore, the locations of lectin binding in schistosomes were compared with those of the antigen-antibody reactions using the fluorescence technique. It was also studied as to whether lectin binding influenced antigen-antibody reactions. Thus it was found that most lectin binding receptors were located at the same sites, where also FITC-labeled antibodies reacted. But antibodies did not inhibit lectin binding on schistosomes, whereas lectins blocked the antigenic sites to weaken the following antibody reactions on microscope slides. Con A did not show a distinguished pattern on schistosomes, although its carbohydrate specificity was confirmed. On the contrary, the WGA reactions were hardly considered to be carbohydrate specific. PNA and SBA receptors, however, were selectively detected in the egg, testes and adult tegument of schistosomes, corresponding to the sites, where also egg antigenicity was observed. But in the gut of adult schistosomes, in which egg antigenicity was not found, lectin binding with PNA, SBA, UEA 1 and DBA did not occur. Gut reacted only with RCA 120 and Con A. The lectin specificity on tegument of adult schistosomes and on cercaria was similar to that found on egg and testes. The result indicated possibilities of satisfactory purification of schistosomal antigens by using such lectins as PNA, SBA and RCA 120, instead of Con A and WGA, to separate more defined antigenic components.