Schistosome Infection Is Associated With Enhanced Whole-Blood Il-10 Secretion In Response To Cercarial Excretory/Secretory Products

Infection of the human host by schistosome parasites follows exposure of skin to free-swimming cercariae and is aided by the release of excretory/secretory (E/S) material, which is rich in proteases and glycoconjugates. This material provides the initial stimulus to cells of the innate immune system. The study presented here is the first to examine human innate/early immune responsiveness to cercarial E/S in subjects from an area co-endemic for Schistosoma mansoni and S.haematobium. We report that in infected participants, stimulation of whole-blood cultures with cercarial E/S material (termed 03hRP) caused the early (within 24h) release of greater quantities of regulatory IL-10, compared with uninfected controls. Elevated levels of IL-10 but not pro-inflammatory TNF or IL-8 were most evident in participants co-infected with S.mansoni and S.haematobium and were accompanied by a higher 03h RP-specific IL-10: TNF ratio. We also report that glycosylated components within 03h RP appear to be important factors in the stimulation of IL-8, TNF and IL-10 production by whole-blood cells.