Milk-sphingomyelin, but not egg-ceramide, engaged the iNKT-TCR and induced iNKT proliferation and T-helper 2 (Th2)-type IL-4 secretion. Children with food allergy had significantly fewer peripheral blood iNKTs which exhibited a greater Th2 response to α-GalCer and milk sphingomyelin compared to iNKTs of healthy controls. This evidence concerns the gene IL4 and food allergy.