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

Monday, October 24, 2022

3:00 PM – 5:00 PM ET

Location: Crown Ballroom

Has Audio

Presenting Author(s)

Christopher J. Lee, MD

University of North Carolina
Chapel Hill, North Carolina

Sarah K. McGill, MD, MSc¹, Michael E. Levin, MBBS², Nicholas J. Shaheen, MD, MPH¹, Cary C. Cotton, MD, MPH¹, Christopher J. Lee, MD¹, Scott P. Commins, MD, PhD¹
¹University of North Carolina, Chapel Hill, NC; ²University of Cape Town, Cape Town, Western Cape, South Africa

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.

Figure: Characteristics that predicted a GI-Isolated reaction to mammalian meat challenge, by univariate analysis.

Characteristic	GI-Isolated Symptoms (n=37)	Systemic Symptoms (n=54)	P Value
Gender, n (%)
Female	25 (67.6%)	33 (61.1%)	0.66*
Male	12 (32.4%)	21 (38.9%)
Age, Median range; IQR	11 (5-57; 8-13)	17 (4-65; 9-38)	0.03**
Age< 18 (%)	28 (75.7%)	28 (51.8%)	0.03*
Onset of symptoms in minutes, median (range; IQR)	90 (45-330; 75-120)	120 (45-375; 100-185)	< 0.003**
Alpha-gal IgE U/L, median (range; IQR)	18.7 (0.7-74.7; 4-35)	10.45 (0.9-344.5; 4.5-25)	0.23**
History of Tick Bite	7 (18.9%)	12 (22.2%)	0.8*

Table: Characteristics of patients with GI-isolated symptoms and those with systemic symptoms on oral food challenge.

IQR, Interquartile ratio; U/L Units per litre
P-values calculated with * Fisher’s exact and ** Mann-Whitney ranksum.

Disclosures:

Sarah McGill: Abbott Laboratories – Stock-publicly held company(excluding mutual/index funds). Finch Pharmaceuticals – Grant/Research Support. Olympus America – Grant/Research Support. Seattle Genetics – Stock-publicly held company(excluding mutual/index funds).

Michael Levin: African Paediatric Fellowship Programme – Grant/Research Support. Allergy Society of South Africa – Grant/Research Support. Department of Paediatrics at Red Cross Hospital – Grant/Research Support. Discovery Foundation – Grant/Research Support. Nestle Nutrition Institute Africa – Grant/Research Support. Thermo-Fisher South Africa – Grant/Research Support.

Nicholas Shaheen indicated no relevant financial relationships.

Cary Cotton indicated no relevant financial relationships.

Christopher Lee indicated no relevant financial relationships.

Scott Commins: CDC – Grant/Research Support. Genentech – Speakers Bureau. NIH – Grant/Research Support. UpToDate – Royalties.

Sarah K. McGill, MD, MSc¹, Michael E. Levin, MBBS², Nicholas J. Shaheen, MD, MPH¹, Cary C. Cotton, MD, MPH¹, Christopher J. Lee, MD¹, Scott P. Commins, MD, PhD¹. C0278 - Gastrointestinal-Isolated Distress Is Common in Alpha-Gal Allergic Patients on Oral Challenge, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.