ABSTRACT
Allergic reactions to food can be broadly classified based upon their pathogenic mechanisms as IgE-mediated, non-IgE-mediated, and combined IgE/non-IgE-mediated reactions. In clinical practice, IgE-mediated food allergies are relatively easier to diagnose compared with the other types because they mostly manifest sooner (a few minutes to hours) after food allergen exposure and specific IgE-based diagnostic tests are available. The most common clinical non-IgE-mediated allergies include food protein-induced allergic enterocolitis syndrome (FPIES), food protein enteropathy, and food protein-induced allergic proctocolitis (FPIAP). Conditions such as eosinophilic esophagitis (EoE), other eosinophilic gastrointestinal diseases (EGID), and atopic dermatitis are mediated by both IgE- and non-IgE-mediated pathways. The pathogenesis of FPIES is not clear. However, robust actuation of innate immune mechanisms after food ingestion has been implicated. The pathogenic mechanism of EoE remains elusive but involves a complex interaction between various factors, including genetic, environmental, and host immune response to ingested food allergens leading to the development of mucosal infiltration by eosinophils.
