Eosinophil chemotactic factor in schistosome eggs: a comparative study of eosinophil chemotactic factors in the eggs of Schistosoma japonicum and S. mansoni in vitro.

Significant chemotactic activity for eosinophils was detected in soluble egg antigen (SEA) preparations of both Schistosoma japonicum and S. mansoni in dose-dependent fashion. The activity of S. japonicum SEA was higher than that of S. mansoni SEA. Gel filtration on Sephadex G-150 showed that S. japonicum SEA was composed of two groups of eosinophil chemotactic factors (ECFs), one of high molecular weight (JEE-H) and the other of low molecular weight (JEE-L). S. mansoni SEA showed ECF composition similar to that of S. japonicum SEA. JEE-H was stable on heating (100 degrees C, 60 min) and resistant to pronase digestion, but was sensitive to periodate oxidation. JEE-L was also stable on heating and resistant to pronase and carboxypeptidase A digestions. These properties of the ECFs were also held in common with those of S. mansoni SEA. JEE-L was extractable by toluene, indicating a hydrophobic nature. These results suggest that schistosome eggs themselves contain ECFs, and that the composition of S. mansoni and S. japonicum SEA-derived ECFs is essentially the same. However, they differ from the other ECFs which have already been described in schistosome infections.