Food Allergy and Anaphylaxis Research (6)Allergic Rhinitis and Sensitization (4)Vector-borne infectious diseases (3)Mast cells and histamine (2)Xenotransplantation and immune response (2)
Ailsworth SM, MacCallum M, Richards NE, Workman LJ, Schoppee Bortz P, et al.
Antibodies (Basel, Switzerland) •
Antibodies to galactose-alpha-1,3-galactose (alpha-gal), particularly the IgM and IgG isotypes, are abundant in human sera. These antibodies are known to be an important xenotransplantation barrier, but the full implications of these antibodies to health and disease remain incompletely understood. By contrast, IgE to alpha-gal is uncommon in the population but has been associated with tick bites and causally linked with mammalian meat allergy, often now known as alpha-gal syndrome (AGS). To date, there have been few population-based studies that have investigated alpha-gal IgG levels in relation to demographic factors, diet, tick bites, and mammalian meat allergy. Adults, predominantly healthcare workers, were recruited for a COVID-19 vaccine study. At least one serum sample was collected, and subjects completed questionnaires to provide demographic, diet, and tick exposure data. Alpha-gal IgG, IgE, and total IgG were measured using the ImmunoCAP platform, and blood group was assessed via reverse typing using stored serum. We also assessed alpha-gal IgG levels among subjects with AGS, recruited from an allergy clinic. The median age of the 267 subjects in the vaccine cohort was 42 years, and median alpha-gal IgG levels were 3.0 μg/mL. Alpha-gal IgG levels were higher among the 43 (16.1%) subjects who had alpha-gal IgE sensitization (≥0.1 IU/mL) and among subjects lacking the B blood group antigen (blood groups A and O). Alpha-gal IgG levels did not differ between the subjects who had asymptomatic alpha-gal IgE sensitization and those who had meat allergy. However, both groups had higher alpha-gal IgG levels than subjects who lacked alpha-gal IgE sensitization. Subjects who reported prior tick or chigger bites had higher alpha-gal IgG levels than those without a bite history, regardless of alpha-gal IgE sensitization status. In a population-based cohort, alpha-gal IgG antibodies were found to be prevalent, and levels were increased in subjects with blood groups A and O, subjects who were alpha-gal IgE sensitized, and those who reported a history of tick bites.
The journal of allergy and clinical immunology. In practice •
IgE to galactose-alpha-1,3-galactose (alpha-gal) is linked to tick bites and an important cause of anaphylaxis and urticarial reactions to mammalian meat. The alpha-gal syndrome (AGS) is recognized as being common in the southeastern United States. However, prevalence studies are lacking and open questions remain about risk factors and clinical presentation of alpha-gal sensitization. Here we characterized the prevalence as well as the presentation and risk factors of AGS and alpha-gal IgE sensitization in adults in central Virginia recruited without regard to the history of allergic disease. Adults in central Virginia, primarily University of Virginia Health employees, were recruited as part of a COVID-19 vaccine study. Subjects provided at least one blood sample and answered questionnaires about medical and dietary history. We used ImmunoCAP for IgE assays and assessed the ABO blood group by reverse typing using stored serum. We also investigated biobanked serum from COVID-19 patients. Median age of the 267 enrollees was 42 years, 76% were female, and 43 (16%) were sensitized to alpha-gal (cutoff of 0.1 IU/mL), of which mammalian meat allergy was reported by seven (2.6%). Sensitized subjects (1) were older, (2) had higher total IgE levels but a similar frequency of IgE to common respiratory allergens, and (3) were more likely to report tick bites than were nonsensitized subjects. Among those who were sensitized, alpha-gal IgE levels were higher among meat-allergic than nonallergic subjects (geometric mean, 9.0 vs 0.5 IU/mL; P < .001). Mammalian meat and dairy consumption was common in individuals with low-level sensitization. In central Virginia, AGS is a dominant cause of adult food allergy with a prevalence approaching or exceeding 2%.
Platts-Mills TAE, MacCallum MH, Wilson JM, Workman LJ, Erwin EA
Frontiers in allergy •
From the earliest days of studying the reagins in allergic sera that give rise to the Prausnitz-Kuestner reaction, there was evidence that there were other types of antibodies (Ab) specific for allergens, particularly those induced by immunotherapy. By 1980, not only was IgE recognized and could be measured, but the presence of other isotypes including IgG and IgA in patients with IgE was well established. From that time onwards the development of monoclonal antibodies made it possible to distinguish and measure antibodies of other isotypes such as IgG4, IgG2, and IgG3. Over the past 40 years two things have dominated the field- firstly, the techniques for measuring isotype specific antibodies to allergens have improved steadily. Secondly, several different allergic diseases or phenomena have been identified in which isotype diversity of the antibodies has become a major issue. Prior to 1990 only occasional cases of eosinophilic esophagitis (EoE) had been identified, but since then they have become common. Most of the cases have positive skin tests and/or IgE Ab to cow's milk or wheat, but it became obvious that most cases of EoE are not primarily related to IgE. Today it is clear that IgG4 Ab to these allergens play a significant role in cases of EoE. In 2000 the first reports of children developing tolerance to cat allergen appeared. Today it is clear that this tolerance depends on high levels of IgG4 antibodies and there is increasing evidence that the IgG4 response is primarily against . The most recent novel allergic disease is the alpha-gal syndrome (AGS). This condition is based on IgE antibodies specific for the oligosaccharide galactose alpha,1-3-galactose, which are primarily induced by tick bites. However, in this case it was already well known that all immunocompetent primates have made IgG and IgM antibodies to this oligosaccharide. Furthermore, it is not clear whether the IgG isotypes, particularly IgG1 and IgG3, play a role in the inflammatory response to the oligosaccharide. Overall, it is clear that current and future investigation of allergic diseases requires careful assessment of allergen specific antibodies of diverse isotypes in addition to IgE.