Anaphylaxis to Bovine Serum Albumin Tissue Adhesive in a Non–Meat-Allergic Patient

International audienc

The basophil activation test differentiates between patients with alpha-gal syndrome and asymptomatic alpha-gal sensitization.

Background: Galactose-alpha-1,3-galactose (alpha-gal) syndrome is characterized by the presence of serum specific IgE antibodies to alpha-gal and delayed type I allergic reactions to the carbohydrate alpha-gal after consumption of mammalian (red) meat products and drugs of mammalian origin. Diagnostics currently rely on patient history, skin tests, determination of serum specific IgE antibodies, and oral food or drug challenges.Objective: We sought to assess the utility of different basophil parameters (basophil reactivity and sensitivity, the ratio of the percentage of CD63(+) basophils induced by the alpha-gal-containing allergen to the percentage of CD63(+) basophils after stimulation with anti-Fc epsilon RI antibody [%CD63(+)/anti-Fc epsilon RI], and area under the dose-response curve [AUC]) as biomarkers for the clinical outcome of patients with alpha-gal syndrome compared with subjects with asymptomatic alpha-gal sensitization.Methods: In addition to routine diagnostics, a basophil activation test (Flow CAST) with different concentrations of alpha-gal-containing allergens (eg, commercially available alpha-gal-carrying proteins and pork kidney extracts) was performed in 21 patients with alpha-gal syndrome, 12 alphagal-sensitized subjects, and 18 control subjects.Results: Alpha-gal-containing allergens induced strong basophil activation in a dose-dependent manner in patients. Basophil reactivity at distinct allergen concentrations, the % CD63(+)/anti-FceRI ratio across most allergen concentrations, the AUC of dose-response curves, and basophil allergen threshold sensitivity (CD-sens) with pork kidney extract were significantly higher in patients with alpha-gal syndrome compared with those in sensitized subjects. All parameters were negative in control subjects.Conclusion: The basophil activation test should be considered as an additional diagnostic test before performing time-consuming and potentially risky oral provocation tests. The % CD63(+)/anti-Fc epsilon RI ratio for all allergens and AUCs for pork kidney were the best parameters for distinguishing patients with alpha-gal syndrome from subjects with asymptomatic alpha-gal sensitization

Identification of a polygalacturonase (Cup s 2) as the major CCD-bearing allergen in Cupressus sempervirens pollen

International audienceAs IgE glyco‐epitopes, also referred to as cross‐reactive carbohydrate determinants (CCDs), can share significant structural homologies between different plants, they are prone to extensive cross‐reactivity among allergen pollen extracts. Here, cypress pollen allergens, especially a polygalacturonase (PG), were further characterized using double one‐dimensional electrophoresis (D1‐DE). The presence of specific IgE directed against CCDs was investigated by bromelain IgE inhibition and concanavalin A binding assays using sera of cypress pollen‐sensitized patients. Our results showed that IgE reactivity to CCDs in Cupressus sempervirens pollen extracts is mainly related to bromelain‐type epitopes of a newly identified cypress PG. This glycoprotein has been further characterized through an immunoproteomic approach and officially indexed as Cup s 2 by the WHO/IUIS allergen nomenclature. Cup s 2 could thus be associated with the increased prevalence of IgE reactivity to cypress pollen extracts because of CCD interference

α-Gal present on both glycolipids and glycoproteins contributes to immune response in meat-allergic patients.

BACKGROUND: The α-Gal syndrome is associated with the presence of IgE directed to the carbohydrate galactose-α-1,3-galactose (α-Gal) and is characterized by a delayed allergic reaction occurring 2 to 6 hours after ingestion of mammalian meat. On the basis of their slow digestion and processing kinetics, α-Gal-carrying glycolipids have been proposed as the main trigger of the delayed reaction. OBJECTIVE: We analyzed and compared the in vitro allergenicity of α-Gal-carrying glycoproteins and glycolipids from natural food sources. METHODS: Proteins and lipids were extracted from pork kidney (PK), beef, and chicken. Glycolipids were purified from rabbit erythrocytes. The presence of α-Gal and IgE binding of α-Gal-allergic patient sera (n = 39) was assessed by thin-layer chromatography as well as by direct and inhibition enzyme-linked immunosorbent assay. The in vitro allergenicity of glycoproteins and glycolipids from different meat extracts was determined by basophil activation test. Glycoprotein stability was evaluated by simulated gastric and intestinal digestion assays. RESULTS: α-Gal was detected on glycolipids of PK and beef. Patient IgE antibodies recognized α-Gal bound to glycoproteins and glycolipids, although binding to glycoproteins was more potent. Rabbit glycolipids were able to strongly activate patient basophils, whereas lipid extracts from PK and beef were also found to trigger basophil activation, but at a lower capacity compared to the respective protein extracts. Simulated gastric digestion assays of PK showed a high stability of α-Gal-carrying proteins in PK. CONCLUSION: Both α-Gal-carrying glycoproteins and glycolipids are able to strongly activate patient basophils. In PK and beef, α-Gal epitopes seem to be less abundant on glycolipids than on glycoproteins, suggesting a major role of glycoproteins in delayed anaphylaxis upon consumption of these food sources

A novel monoclonal IgG1 antibody specific for Galactose-alpha-1,3-galactose questions alpha-Gal epitope expression by bacteria.

The alpha-Gal epitope (α-Gal) with the determining element galactose-α1,3-galactose can lead to clinically relevant allergic reactions and rejections in xenotransplantation. These immune reactions can develop because humans are devoid of this carbohydrate due to evolutionary loss of the enzyme α1,3-galactosyltransferase (GGTA1). In addition, up to 1% of human IgG antibodies are directed against α-Gal, but the stimulus for the induction of anti-α-Gal antibodies is still unclear. Commensal bacteria have been suggested as a causal factor for this induction as α-Gal binding tools such as lectins were found to stain cultivated bacteria isolated from the intestinal tract. Currently available tools for the detection of the definite α-Gal epitope, however, are cross-reactive, or have limited affinity and, hence, offer restricted possibilities for application. In this study, we describe a novel monoclonal IgG1 antibody (27H8) specific for the α-Gal epitope. The 27H8 antibody was generated by immunization of Ggta1 knockout mice and displays a high affinity towards synthetic and naturally occurring α-Gal in various applications. Using this novel tool, we found that intestinal bacteria reported to be α-Gal positive cannot be stained with 27H8 questioning whether commensal bacteria express the native α-Gal epitope at all