After establishing the requirement for IL-4Rα signaling on B cells in the development of IL-4 producing B cells and optimal Th2 responses to acute schistosomiasis, we questioned whether the development of optimal Th2 responses depends on both the ability of B cells to receive instruction from IL-4 and their ability to secrete IL-4 that triggers Th2 responses during S. mansoni infection. This evidence concerns the gene IL4R and schistosomiasis.