Alpha-Gal allergy : About three Cases

Abstract

Alpha-gal allergy is a rare food allergy characterized by an immune response to Ig E antibodies against galactose 1-3-alpha-galactoside, which is found in red meat and the meat of non-primate mammals. It has also been reported in association with the administration of cetuximab, a monoclonal antibody used as a second-line treatment for locally advanced head and neck cancers. Allergic reactions to alpha-gal present as immediate reactions following intravenous injection of cetuximab or as delayed reactions occurring three to eight hours after consumption of red meat. Clinical manifestations range from hives to gastrointestinal symptoms and, in severe cases, anaphylaxis. Tick bites are the most commonly reported route of sensitization. Patients with blood types B or AB appear to be protected, due to the similarity of the B antigen to alpha-gal in their molecular structure. Diagnosis is based on a consistent clinical history, blood testing for specific anti-alpha-gal Ig E, or ideally a basophil activation test. Currently, there is no curative treatment. Management involves avoiding red meat and offal from non-primate mammals, contraindicating cetuximab and products containing gelatin, and prescribing a medical kit.