Which mediator is primarily associated with the Type 1 hypersensitivity reaction seen in food-responsive enteropathy?

• A. IgG
• B. IgM
• C. IgA
• D. IgE

Answer: (D)

Type I hypersensitivity is driven by IgE antibodies. In this reaction, exposure to a food antigen sensitizes the individual and causes production of antigen-specific IgE that binds to FcεRI receptors on mast cells and basophils. When the allergen is encountered again, it cross-links these IgE molecules, triggering rapid degranulation and release of mediators like histamine and leukotrienes. This immediate mediator release leads to the GI symptoms seen in food-related enteropathy, such as diarrhea, vomiting, and cramping, due to increased intestinal permeability, motility, and mucosal inflammation.

IgG and IgM are more associated with other antibody-mediated processes and hypersensitivities, such as complement-activating cytotoxic or immune complex–mediated reactions, while IgA mainly provides mucosal protection and is not the primary driver of the rapid, IgE-mediated response described here.