We demonstrate that CD193, the eotaxin receptor, is highly expressed on circulating B cells in paediatric
schistosomiasis mansoni. CD193 plays a role in directing granulocytes into sites of allergic-like
inflammation in the mucosa, but little is known about its functional significance on human B cells. We sought to characterize CD193 expression and its relationship with S. mansoni
infection. We found that CD193+ B cells increased with the intensity of schistosome
infection. In addition, a significant negative association was observed between CD193 expression by B cells and
IgE production. Decreased
IgE levels are generally associated with susceptibility to
re-infection. B cell stimulation with
eotaxin-1 increased CD193 levels whereas
IL-4 led to a reduction. This was supported by plasma levels of
eotaxin-1 correlating with CD193 levels on B cells and other cells. In contrast, CD193 expression was induced on naive B cells with a combination of
IL-10 and schistosome
antigens. Whereas T cells had a modest increase in CD193 expression, only B cell CD193 appeared functionally chemotactic to
eotaxin-1. Thus, CD193+ B cells, which co-express CXCR5, may be enroute to sites with allergic-like
inflammation, such as gastrointestinal follicles, or even to Th2
granulomas, which develop around parasite eggs. Overall, our results suggest that schistosome
infection may promote CD193 expression and suppress
IgE via
IL-10 and other undefined mechanisms related to B cell trafficking. This study adds to our understanding of why young children may have poor immunity. Nonetheless,
praziquantel treatment was shown to reduce percentages of circulating CD193+ B cells lending hope for future
vaccine efforts.