FcRn is mother's milk to allergen tolerance.

In this issue Ohsaki et al. (https://doi.org/10.1084/jem.20171163) explain how breastfeeding can prevent the onset of food allergies in offspring by instructing T reg formation via neonatal Fc receptor (FcRn)-mediated transfer and uptake of allergen-containing IgG immune complexes (Ig-ICs) by gut dendritic cells (DCs).