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&alpha, Gal syndrome (AGS) is a type of anaphylactic reaction to mammalian meat characterized by an immunoglobulin (Ig)E immune response to the oligosaccharide &alpha, Gal (Gal&alpha, 1-3Gal&beta, 1-4GlcNAc-R). Tick bites seems to be a prerequisite for the onset of the allergic disease in humans, but the implication of non-tick parasites in &alpha, Gal sensitization has also been deliberated. In the present study, we therefore evaluated the capacity of helminths (Toxocara canis, Ascaris suum, Schistosoma mansoni), protozoa (Toxoplasma gondii), and parasitic fungi (Aspergillus fumigatus) to induce an immune response to &alpha, Gal. For this, different developmental stages of the infectious agents were tested for the presence of &alpha, Gal. Next, the potential correlation between immune responses to &alpha, Gal and the parasite infections was investigated by testing sera collected from patients with AGS and those infected with the parasites. Our results showed that S. mansoni and A. fumigatus produce the terminal &alpha, Gal moieties, but they were not able to induce the production of specific antibodies. By contrast, T. canis, A. suum and T. gondii lack the &alpha, Gal epitope. Furthermore, the patients with T. canis infection had significantly decreased anti-&alpha, Gal IgE levels when compared to the healthy controls, suggesting the potential role of this nematode parasite in suppressing the allergic response to the glycan molecule. This rather intriguing observation is discussed in the context of the &lsquo, hygiene hypothesis&rsquo, Taken together, our study provides new insights into the relationships between immune responses to &alpha, Gal and parasitic infections. However, further investigations should be undertaken to identify T. canis components with potent immunomodulatory properties and to assess their potential to be used in immunotherapy and control of AGS.

Poultry meat can induce severe allergic reactions. So far, the molecules causing poultry meat allergy are largely unknown.Our aim was to identify and characterize poultry meat allergens.Profiles of patients' IgE reactivity to chicken muscle were analyzed in immunoblots, and proteins recognized by the majority of patients were subjected to peptide mass fingerprinting. A 23-kDa IgE-reactive protein was identified as myosin light chain 1, designated Gallus domesticus 7 (Gal d 7). Recombinant Gal d 7 was produced in Escherichia coli. The protein's IgE reactivity was analyzed in ELISA experiments, and cross-reactivity with allergens of other poultry species was assessed in inhibition immunoblots. Fold and thermal stability were evaluated by circular dichroism analysis, and enzymatic stability was investigated using in vitro gastrointestinal digestion assays.Recombinant Gal d 7 represents a properly folded, predominantly α-helical protein and displays IgE-binding activity comparable to that of its natural counterpart. IgE reactivity analysis in 28 patients allergic to chicken meat revealed that Gal d 7 is a major allergen for patients primarily sensitized to chicken meat. Furthermore, Gal d 7-cross-reactive allergens were also detected in other poultry species, suggesting that recombinant Gal d 7 can be used as a diagnostic marker allergen for poultry meat allergy. The high thermal stability, refolding capacity, and resistance to gastrointestinal enzymes might explain why Gal d 7 can act as a potent sensitizing agent.Gal d 7 represents a novel major chicken meat allergen. Recombinant Gal d 7 could be used for diagnosis of genuine poultry meat sensitization.

Background The oligosaccharide galactose‐α‐1,3‐galactose (α‐Gal), present in mammalian proteins and lipids, causes an unusual delayed allergic reaction 3 to 6 hours after ingestion of mammalian meat in individuals with IgE antibodies against α‐Gal. To better understand the delayed onset of allergic symptoms and investigate whether protein‐bound or lipid‐bound α‐Gal causes these symptoms, we analyzed the capacity of α‐Gal conjugated proteins and lipids to cross a monolayer of intestinal cells. Methods Extracts of proteins and lipids from beef were prepared, subjected to in vitro digestions, and added to Caco‐2 cells grown on permeable supports. The presence of α‐Gal in the basolateral medium was investigated by immunoblotting, thin‐layer chromatography with immunostaining and ELISA, and its allergenic activity was analyzed in a basophil activation test. Results After addition of beef proteins to the apical side of Caco‐2 cells, α‐Gal containing peptides were not detected in the basolateral medium. Those peptides that crossed the Caco‐2 monolayer did not activate basophils from an α‐Gal allergic patient. Instead, when Caco‐2 cells were incubated with lipids extracted from beef, α‐Gal was detected in the basolateral medium. Furthermore, these α‐Gal lipids were able to activate the basophils of an α‐Gal allergic patient in a dose‐dependent manner. Conclusion Only α‐Gal bound to lipids, but not to proteins, is able to cross the intestinal monolayer and trigger an allergic reaction. This suggests that the slower digestion and absorption of lipids might be responsible for the unusual delayed allergic reactions in α‐Gal allergic patients and identifies glycolipids as potential allergenic molecules., α‐Gal is present in both lipids and proteins from beef, but only when it is bound to beef lipids, the oligosaccharide can cross the Caco‐2 cell monolayer. α‐Gal carried by lipids is packaged by the enterocytes into chylomicrons, which are then able to activate the basophils of an α‐Gal allergic patient. The slower in vivo digestion and absorption of lipids explain the delayed allergic reactions to α‐Gal. α‐Gal: galactose‐ α‐1,3‐galactose