The effect of this upregulation of Th2 pathway signaling on T cell resistance following preparation of the recipient mice with TBI was direct because helminth infection did not lead to a similar increase in the number of surviving T cells in CKO mice (Fig. 5), in agreement with recipient T cell counts after BMT in recipients with T cell–specific IL-4Rα deficiency (Table I). Here, IL4R is linked to helminthiasis.