nonIgEmediated

NonIgEmediated, often written as non-IgE-mediated, refers to immune reactions to allergens that are not mediated by IgE antibodies. These reactions are distinct from classic IgE-mediated allergies and typically produce symptoms through cell-mediated or other non-IgE pathways. They generally have a delayed onset after exposure to the trigger, ranging from several hours to days, rather than occurring within minutes.

In clinical practice, non-IgE-mediated reactions are most discussed in the context of food allergy, particularly in infants and young children. The best-known conditions include food protein-induced enterocolitis syndrome (FPIES), food protein-induced enteropathy (FPE), and food protein-induced allergic proctocolitis (FPIAP). FPIES presents with repeated vomiting, diarrhea, pallor, and lethargy hours after ingestion of a triggering food, and can lead to dehydration or shock in severe cases. FPIAP causes blood-tinged stools in otherwise healthy-appearing infants, while FPE features chronic diarrhea and malabsorption with possible growth concerns. Unlike many IgE-mediated allergies, skin prick tests and serum specific IgE tests are usually negative in these conditions.

Diagnosis relies on clinical history, symptom timing, and observed responses to food elimination and reintroduction, with oral food challenges conducted under medical supervision as needed. Management centers on eliminating the identified trigger foods while ensuring balanced nutrition. Most children outgrow non-IgE-mediated food allergies over time, though the age of resolution and the specific prognosis vary by condition. Ongoing research seeks to clarify pathophysiology and improve diagnostic approaches.