These reports have shown that TGF-β is required for helminth-induced suppression of colitis (41), multiple sclerosis (42), or GVHD (18), and also demonstrated that helminth products, instead of live helminths, promote immune regulation in a TGF-β–dependent manner, thereby contributing to regulation of reactive airway disease (40) in mice. This evidence concerns the gene TGFB1 and colitis.