ABSTRACT
BACKGROUND: Human type 2 cytokine responsiveness to schistosome antigens increases after treatment; due either to removal of the immunosuppressive effects of active infection or immunological boosting by antigens released from dying parasites. We determined the responsiveness to Schistosoma mansoni over a 2-year period, when reinfection was restricted by interrupting transmission. METHODS: The proinflammatory and type 2 responses of Kenyan schoolchildren were measured before, and 1 year and 2 years posttreatment in whole blood cultures stimulated with soluble egg antigen (SEA) or soluble worm antigen (SWA). The site of S. mansoni transmission was molluscicided throughout. RESULTS: Pretreatment proinflammatory responses to SEA were high but reduced 1 and 2 years posttreatment, whereas type 2 responses were low pretreatment and increased 1 and 2 years posttreatment. Type 2 responses to SWA were high pretreatment and increased at 1 year, with no further increases at 2 years posttreatment. Children infected at follow-up had lower SEA, but not SWA, posttreatment type 2 responsiveness. Increases at 1 year in type 2 SWA, but not SEA, responsiveness correlated with pretreatment egg counts. CONCLUSIONS: Removal of immunosuppressive effects of active infection increases SEA type 2 responsiveness; long-term SWA type 2 responsiveness is due to treatment-induced immunological boosting. Dissociation of type 2 responses potentially protects against severe egg-associated immunopathology during infection, while allowing worm-antigen derived immunity to develop.
