Hawrylowicz et al. recently showed an interesting hypothesis that the apparent beneficial association of vitamin D in allergies in vivo, which in many patients is a TH2-type cytokine pathology, suggests that the direct action of vitamin D in promoting TH2 lymphocyte responses is less important in vivo than other vitamin D–mediated mechanisms (eg, vitamin D upregulated production of soluble decoy receptor, an inhibitor of IL-33 in situ in the airways mucosa, and the induction of regulatory mechanisms) in inhibiting TH2-type cytokine responses[23]. This evidence concerns the gene IL33 and allergic disease.