The Role of Intestinal Dendritic Cells in Inducing Th2 Responses to Injected Schistosoma mansoni eggs

Schistosoma mansoni eggs (SME), which are the main cause of chronic Schistosomiasis, provoke a strong Th2 immune response that can lead to granulomatous reactions and fibrosis in affected organs. Recently, CD11c depletion has been shown to severely disrupt Th2 immune responses against Schistosoma mansoni, suggesting that antigen presenting cells, which express CD11c, mediate this immune response. Dendritic cells (DCs) are the most likely CD11c-positive candidates, as they continuously migrate from epithelia, carrying antigens, to the draining lymph nodes where they activate naive T-cells. However, the precise roles of DCs in inducing immune responses against SME have not been studied.

We have developed an in vivo mouse model where we inject SME in the subserosal layer of the small intestine of C57BL/6 mice, the anatomical location where SME naturally become lodged. This provokes a Th2 response in the draining mesenteric lymph nodes (MLNs). To test the role of DCs in this response, we will purify migrating DCs from egg challenged mice and control animals and then inject these cells into the subcapsular region of the MLN of naive mice. Detection of an antigen-specific Th2 response in those mice will indicate that migratory DCs are sufficient to carry and present egg antigens and drive Th2 responses in our model.

This knowledge will contribute to a better understanding of how the early immune response against SME is mediated. This information can be applied to battle chronic Schistosomiasis and may help understand Th2 driven responses against other parasites or Th2 allergic responses.