FOXP3 and helminthiasis: Although Hp‐TGM has no structural homology with mammalian TGF‐β, it is a potent inducer of mouse and human Foxp3+ Treg cells in vitro. Elaboration of a factor that drives Treg induction argues that their expansion during helminth infection is not merely a host homeostatic mechanism to rein in overstimulation but an adaptive evolutionary strategy on the part of the parasite to maximize their survival in an immune environment.