α-Gal Syndrome vs Chronic Urticaria

Abstract

Galactose-α-1,3-galactose (α-gal) is an oligosaccharide expressed on glycoproteins and glycolipids of nonprimate mammals and is the causal epitope of an IgE-mediated allergy to mammalian meat. 1,2 First reported in 2009, the α-gal syndrome is an increasingly appreciated problem across the southeastern United States and other parts of the world. 2 It is clear that tick bites, specifically relating to Amblyomma americanum (lone star tick), are causal in many, if not most, cases of α-gal sensitization in the United States. 3 Following sensitization, many individuals will experience allergic symptoms on ingestion of meat or other products (eg, dairy) derived from nonprimate mammals. In contrast to typical IgE-mediated reactions, which occur within minutes of exposure, the α-gal allergy typically has a delayed onset of 2 to 6 hours. 2 The severity of the reaction varies from general urticaria to anaphylaxis, and individuals may not react to every exposure. Because of these atypical features, proper diagnosis can prove challenging. An epidemiological investigation of a pediatric population reported that α-gal may be misdiagnosed as recurrent urticaria or idiopathic anaphylaxis. 4 While a recent report postulated that α-gal syndrome might represent a novel cause of chronic urticaria, further research failed to find such an association. 5,6 Nevertheless, in areas where α-gal sensitization is prevalent, the potential for misdiagnosing cases of α-gal syndrome as chronic urticaria still exists. Here, we report cases labeled as chronic urticaria or chronic idiopathic urticaria within a cohort of patients in central Virginia being evaluated for α-gal syndrome.

COVID-19 variants as moving targets and how to stop them by glycoengineered whole-virus vaccines

“…It is suggested that inactivated SARS-CoV-2 whole virus could serve as effective multiantigenic vaccine if it is glycoengineered to present multiple α-gal epitopes in order to achieve anti-Gal mediated targeting to APC for extensive uptake of the vaccinating virus by these cells. Since few individuals produce anti-Gal IgE causing meat allergy to α-gal epitopes in beef, pork and lamb ("α-gal syndrome") [18,19], those with this syndrome should receive vaccines presenting α-gal epitopes in clinics equipped for treating allergic reactions. Vaccinating SARS-CoV-2 α-gal binds the natural anti-Gal antibody at the vaccination site and activates the complement system to generate complement cleavage chemotactic peptides that recruit APC such as dendritic cells and macrophages.…”

Increasing Efficacy of Enveloped Whole-Virus Vaccines by In situ Immune-Complexing with the Natural Anti-Gal Antibody

“…However, the safety of virus-gal vaccines should be determined in particular in individuals with the "-gal syndrome" who are allergic to -gal epitopes in meat such as beef, pork and lamb. [91][92][93] In these individuals, bites by certain ticks in different continents (e.g., Amblyomma americanum in the USA) result in isotype switch for production of anti-Gal IgE. The binding of this IgE antibody to the multiple -gal epitopes in red meat results in an allergic immune response which appears within several hours following eating red meat.…”

Using Symptoms and Healthcare Encounters to Capture a Rare Disease: A Study of Clinical Notes of the Alpha‐Gal Meat Allergy

“…Specifically, food allergies and chronic urticaria appear to be two of the most common differentiating cases. While differentiation with other food allergies can be easier to determine due to delay of symptom onset with AGS (Cabezas‐Cruz et al, 2019), the delayed reaction to meat can also become a confounding factor to prevent easy differentiation with chronic urticaria, not to mention that AGS and chronic urticaria can co‐exist and some even postulate a possible causal relation between the two (Pollack et al, 2019).…”