C0278 - Gastrointestinal-Isolated Distress Is Common in Alpha-Gal Allergic Patients on Oral Challenge

Introduction: Alpha-gal allergy causes a delayed reaction to mammalian meats and has been reported worldwide. Patients with the allergy may present with isolated gastrointestinal (GI) symptoms, but this phenotype is poorly understood.

Methods: We pooled and analyzed symptoms and demographics of patients from two prospective cohorts of patients with diagnosis of alpha-gal allergy who reacted after eating mammalian meat under observation. We compared characteristics of patients who demonstrated GI-isolated symptoms on challenge with those who exhibited symptoms outside the GI tract (skin, respiratory, circulatory).

Results: Among the 91 children and adult alpha-gal allergic patients who exhibited symptoms after oral challenge with mammalian meat, 72.5% experienced GI distress with one or more GI symptoms, which was the most frequent class of symptoms, compared to skin changes in 57.1% and respiratory distress in 5.5%. The most common GI symptoms were abdominal pain (71.0%) and vomiting (22.0%). GI-isolated symptoms occurred in 37 patients (40.7%) who reacted. These patients reacted more quickly than patients who exhibited systemic symptoms (median onset of symptoms in GI-isolated group 90 minutes vs. 120 minutes), were more likely to be children than adults (RR=1.94, 95% CI 1.04-3.63), and had a higher median alpha-gal IgE. The distribution of sex and self-reported history of tick bites was similar in the GI-isolated group versus those with systemic symptoms.

Discussion: Isolated GI distress occurred in 4 in 10 alpha-gal allergic individuals who developed symptoms on oral food challenge with mammalian meat. GI isolated symptoms may be a result of differences in GI mast cell numbers, high-affinity IgE receptor expression levels, or variations in the numbers of gut microbes responsible for stimulating the endogenous anti-alpha-gal IgA, IgM and IgG responses. Further prospective studies are necessary to better understand the epidemiology, pathophysiology, and manifestations of GI-isolated alpha-gal allergy. Alpha-gal allergic patients, particularly children, may exhibit GI distress alone, and adult and pediatric gastroenterologists should be aware of the diagnosis and management of the allergy.