De novo food allergy is a common phenomenon among pediatric solid organ recipients (8.5%-57%) when compared with the general population (0.45%-10%). Other associated disorders include non–IgE-mediated immune reactions and clinical predisposition to asthma and alterations in the oral mucosa. Originally, passive mechanisms (passive transfer of IgE and immune cells) were thought to be responsible for acute, transient cases of food allergies with a previous history of sensitization for a specific allergen in the donor. Recently proposed pathophysiological mechanisms to explain de novo allergies include TH2/B-cell imbalance, regulatory T-cell (Treg) disruption, gastrointestinal immaturity, and altered gastrointestinal permeability. Recent studies also suggest that immunosuppressive drugs, especially tacrolimus, promote naïve T-cell differentiation into TH2 cells, IgE-promoting cytokine production, decreased IL-5 and IL-10 levels, increased IgA levels, and Treg disruption. Such immunological interactions, in conjunction with altered intestinal permeability, intestinal immaturity in children, history of viral infection, and a personal history of allergies or eczema, are thought to explain most clinical cases of pediatric de novo food allergy after solid organ transplantation reported in the literature. A better understanding of the immunological mechanisms underpinning organ donors and recipients may unveil some of the caveats concerning therapeutic management and improve the quality of life of affected individuals.

Key words: Allergies, Transplant, Pediatric, Calcineurin inhibitors, Treg, TH17, TH2