PDCD1 and anaphylaxis: These studies demonstrated that the epicutaneous sensitization with food antigen results in an expansion of Treg with PD-1/PD-L1 exposure and the production of tolerance to the product when there was prior induction in MLN and mast cells or intestinal DCs, and when not, the presence of IgE-mediated anaphylaxis following the oral challenge with prior induction in the skin [121].