NonIgE

NonIgE refers to forms of allergic or hypersensitivity reactions that do not involve immunoglobulin E antibodies. These reactions, often called non–IgE-mediated or non–IgE hypersensitivity, are typically delayed in onset, usually appearing hours to days after exposure. They can affect the gastrointestinal tract, skin, or other organ systems and are distinguished from IgE-mediated allergies by negative IgE testing and a reliance on clinical history, elimination diets, and supervised reintroduction when appropriate.

The best-known examples are non-IgE-mediated food allergies. Food protein-induced enterocolitis syndrome (FPIES) is a prototypical condition in which ingestion of certain foods, most commonly cow’s milk and soy in infancy, triggers repetitive vomiting, pallor, lethargy, and sometimes diarrhea. Acute reactions may require intravenous fluids and antiemetic treatment, while chronic or frequent exposure may affect growth. Food protein-induced allergic proctocolitis (FPIAP) presents with blood-streaked stools in otherwise healthy infants and usually improves with elimination of trigger proteins, resolving in infancy. Food protein-induced enteropathy or enteritis (FPE) involves chronic diarrhea and malabsorption, with improvement after dietary avoidance.

Diagnosis relies on careful clinical history and evidence of negative IgE tests, with oral food challenges used in some cases under medical supervision to confirm tolerance. Management centers on avoiding identified trigger foods and ensuring adequate nutrition, with gradual, monitored reintroduction to assess resolution. Prognosis varies by condition, but many non-IgE-mediated food allergies lessen or resolve in early childhood, though timing can differ.