Scope: Edible insects contain allergens with potential cross‐reactivity to other invertebrates. Here, this study examines IgE‐reactive proteins in a house cricket snack (Acheta domesticus) leading to an allergic reaction in a 27‐year old man followed by a similar reaction days later after eating shrimps.Methods and results: Prick to prick tests verify the IgE‐mediated allergy to crickets and skin prick testing confirms a type I sensitization to house dust mite without any clinical relevance for the patient, and to shrimp extracts, but is negative for several other foods. Serological testing reveals a sensitization to shrimps, shrimp tropomyosin, and house dust mite tropomyosin. IgE‐immunodetection shows that the cricket allergic patient is sensitized to two proteins of 45 and >97 kDa using aqueous control cricket extract, but to only one protein at around 45 kDa when using the causative, seasoned insect snack extract. Mass spectrometry data and IgE‐inhibition experiments clearly identify this protein belonging to the tropomyosin allergen family.Conclusion: This case report suggests that cricket tropomyosin may be an elicitor of allergic reactions even in previously not allergic patients, although it cannot be excluded the patient reacted additionally to other ingredients of the snack.

Plant lipid transfer proteins are a large family that can be found in all land plants. They have a hydrophobic cavity that allows them to harbor lipids and facilitates their traffic between membranes. However, in humans, this plant protein family is responsible for the main food allergies in the Mediterranean area. Nevertheless, not only the protein itself but also its ligand is relevant for allergic sensitization. The main aim of the present work is to analyse the natural ligands carried by four allergenic LTPs (Tri a 14, Art v 3, Par j 2, and Ole e 7), compared with the previously identified ligand of Pru p 3 (CPT-PHS ligand), and clarify their role within the immunological reactions. Results showed that the ligands of the LTPs studied shared a chemical identity, in which the presence of a polar head was essential to the protein-ligand binding. This ligand was transported through a skin cellular model, and phosphorylated phytosphingosine could be detected as result of cell metabolism. Since sphingosine kinase 1 was overexpressed in keratinocytes incubated with the LTP-ligand complex, this enzyme might be responsible for the phosphorylation of the phytosphingosine fraction of the CPT-PHS ligand. This way, phytosphingosine-1-phosphate could be mimicking the role of the human inflammatory mediator sphingosine-1-phosphate, explaining why LTPs are associated with more severe allergic responses. In conclusion, this work contributes to the understanding of the chemical nature and behavior of lipid ligands carried by allergens, which would help to gain insight into their role during allergic sensitization.

Scope: Chickpea (Cicer arietinum) allergy has frequently been reported particularly in Spain and India. Nevertheless, chickpea allergens are poorly characterized. The authors aim to identify and characterize potential allergens from chickpea.Methods and Results: Candidate proteins are selected by an in silico approach or immunoglobuline E (IgE)‐testing. Potential allergens are prepared as recombinant or natural proteins and characterized for structural integrity by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE), circular dichroism (CD)‐spectroscopy, and mass spectrometry (MS) analysis. IgE‐sensitization pattern of Spanish chickpea allergic and German peanut and birch pollen sensitized patients are investigated using chickpea extracts and purified proteins. Chickpea allergic patients show individual and heterogeneous IgE‐sensitization profiles with extracts from raw and boiled chickpeas. Chickpea proteins pathogenesis related protein family 10 (PR‐10), a late embryogenesis abundant protein (LEA/DC‐8), and a vicilin‐containing fraction, but not 2S albumin, shows IgE reactivity with sera from chickpea, birch pollen, and peanut sensitized patients. Remarkably, allergenic vicilin, DC‐8, and PR‐10 are detected in the extract of boiled chickpeas.Conclusion: Several IgE‐reactive chickpea allergens are identified. For the first time a yet not classified DC‐8 protein is characterized as minor allergen (Cic a 1). Finally, the data suggest a potential risk for peanut allergic patients by IgE cross‐reactivity with homologous chickpea proteins.

Background: Approximately 70% of individuals allergic to birch pollen (Bet v 1.01 [Bet]) develop a secondary food allergy (e.g., hazelnut: Cor a 1.04 [Cor]), due to allergen cross‐reactivity. However, standard immunotherapy for type I allergies often does not improve the food allergy sufficiently. We analyzed the allergen‐specific and cross‐reactive suppressive capacity of primary human regulatory T cells (Treg) induced by autologous IL‐10‐modulated dendritic cells (IL‐10 DC) in vitro and in vivo. Methods: CD4 ⁺ T cells of patients with birch pollen and associated hazelnut allergies were differentiated into Bet‐specific or non‐specific induced Treg (iTreg). After Bet‐ or Cor‐specific restimulation the phenotype, proliferation, and suppressive capacity of iTreg subsets were analyzed. iTreg function was further investigated in humanized mouse models of airway and intestinal allergy, generated by engraftment of peripheral blood mononuclear cells from allergic donors into immunodeficient animals. Results: After IL‐10 DC priming and allergen‐specific restimulation (Bet or Cor), non‐specific control iTreg remained anergic, whereas Bet‐specific iTreg proliferated extensively and exhibited a regulatory phenotype (enhanced expression of CTLA‐4, PD‐1, TNFR2, IL‐10). Accordingly, activated Bet‐specific iTreg displayed a high capacity to suppress Bet‐ and Cor‐induced responder Th2 cell responses in vitro, indicating induction of both allergen‐specific (birch) and cross‐reactive tolerance (hazelnut). In vivo, the beneficial effect of Bet‐specific iTreg was verified in humanized mouse models of allergic airway and intestinal inflammation, resulting in reduced allergen‐induced clinical symptoms, and immune responses. Conclusion: Human IL‐10 DC‐induced iTreg facilitate allergen‐specific and cross‐reactive tolerance. Therefore, they are potential candidates for regulatory cell therapy in allergic and autoimmune diseases.