In vitro and in vivo induction of neutrophil and eosinophil chemotactic responses by Schistosoma japonicum cercaria.

High neutrophil and eosinophil chemotactic activities of soluble extract of Schistosoma japonicum cercariae (SjCe-ext) were detected in vitro by using blind-well chemotaxis chambers and Millipore filters in a dose-dependent manner. Low doses (total of 0.25 and 2.5 micrograms) of SjCe-ext induced significant neutrophilic infiltrations in normal and S. japonicum-infected (8 week) guinea pig tissues beginning at 2 hr after the intradermal injection. Eosinophilic responses were observed in the infected animals especially in early phase (2-8 hr post-injection of SjCe-ext). SjCe-ext elicited strong immediate skin reactions (at 30 min) in the infected guinea pigs. Possible roles of these chemotactic activities and hypersensitivity reaction in S. japonicum infection are discussed.