PARASITOLOGY

Sometimes Schistosomiasis

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Science  02 May 2014:
Vol. 344, Issue 6183, pp. 450
DOI: 10.1126/science.344.6183.450-c

Schistosomiasis-causing blood flukes infect hundreds of millions of people in tropical regions, but the occurrence of pathology is highly variable, with 5 to 10% of infections becoming severe. Likewise, schistosome infections take very different courses in different strains of mice; a phenomenon that relates to their relative ability to generate lymphocytes classified as CD4+ T helper 17 (TH17) cells. Sick children with blood flukes have also been found to have higher percentages of CD4+ TH17 cells. Ponichtera et al. have now discovered that the antigen-presenting dendritic cells of a mouse strain that develops severe hepatic granulomatous responses to schistosome eggs have a many times greater expression of a C-type lectin receptor called CD209a (a homolog of human ICAM-3–grabbing nonintegrin) on their cell surfaces as compared with a mouse strain that shows little pathology. CD209a is essential for the induction of the cytokines interleukin-1β and interleukin-23 that stimulate CD4+ TH17 cell development. Possibly the pathology of severe schistosomiasis is caused by elevated CD209a levels in some people sensitizing recognition of the fucose-rich glycans that coat the parasites' egg surface.

J. Immunol. 10.4049/ jimmunol.1400121 (2014).

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