Mechanisms of eosinophil accumulation around eggs of Schistosoma japonicum: role of two purified components, allergen and eosinophil chemotactic factor, from soluble egg antigens measured on sensitized guinea pig skin.

Mechanisms of eosinophil response induced by soluble egg antigen (SEA) in Schistosoma japonicum-infected guinea pig tissues were analyzed using two purified components of SEA: major allergenic components (JEAL) and a major eosinophil chemotactic component (ECF-SjE). Eosinophil response to the crude SEA of S. japonicum was detected at the injection site mainly at 2-8 h after the antigenic challenge; this response consisted of two different phases of eosinophil attraction. An early phase (2 h) was mediated by an immediate-type hypersensitivity reaction; JEAL played an important role in mediating this phase of eosinophil response. A late phase (8 h) was mediated by ECF-SjE. Therefore, this phase of eosinophil response was caused by direct eosinophilotactic activity of SEA. These two types of eosinophil response must be important processes in the formation of S. japonicum egg-associated eosinophilic granuloma.