Sensitization Potency of Sunflower Seed Protein in a Mouse Model: Identification of 2S-Albumins More Allergenic Than SFA-8.

SCOPE: Food allergy to sunflower seed (SFS) protein is not frequent and only non-specific lipid transfert protein (nsLTP) Hel a 3 is officially recognized as a food allergen. Out of the eleven seed storage 2S-albumins (SESA) detected in SFS, only SFA-8 allergenicity has been investigated so far. The study aimed then to evaluate SFS protein allergenicity and particularly, to compare the sensitization potency of SESA in a mouse model. METHODS AND RESULTS: The most abundant SESA and nsLTP were isolated from SFS through a combination of chromatographic methods. Purified proteins were then used to measure specific IgG1 and IgE responses in BALB/c mice orally sensitized to different SFS protein isolates. The study, thus, confirmed the allergenicity of SFA-8 and Hel a 3 but mice were also highly sensitized to other SESA such as SESA2-1 or SESA20-2. Furthermore, competitive inhibition of IgE-binding revealed that SFA-8 IgE-reactivity was due to cross-reactivity with other SESA. 11S-globulins were weakly immunogenic and were rapidly degraded in an in vitro model of gastroduodenal digestion. In contrast, Hel a 3, SESA2-1 and SFA-8 were more resistant to proteolysis and gastroduodenal digestion did not affect their IgE-reactivity. CONCLUSIONS: SESA2-1 or SESA20-2 were more potent allergens than SFA-8 in this mouse model. Allergenicity of SESA must be now confirmed in SFS-allergic patients.

Anaphylaxis induced by conlinin, a 2S storage protein in flaxseed

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Immune polarization in allergic patients: role of the innate immune system

Los alérgenos entran en contacto con el sistema inmune como parte de una mezcla heterogénea de compuestos de muy diversa naturaleza. Las fuentes de alérgenos más comunes son los granos de polen, alimentos o restos de animales. Estas fuentes contienen una variedad de componentes inmunomoduladores que pueden desempeñar un papel importante en la inducción de la sensibilización alérgica. La unión de estas moléculas a las células inmunes pueden influir en el resultado inmunológico final. Actualmente, nuestro objetivo es revisar los mecanismos moleculares implicados en el desarrollo de la alergia, y el papel de estos inmunomoduladores en el reconocimiento de alérgenos por las células innatas, que es clave para entender cómo la sensibilización alérgica se desencadena (AU)

Allergens come into contact with the immune system as components of a very diverse mixture. The most common sources are pollen grains, food, and waste. These sources contain a variety of immunomodulatory components that play a key role in the induction of allergic sensitization. The way allergen molecules bind to the cells of the immune system can determine the immune response. In order to better understand how allergic sensitization is triggered, we review the molecular mechanisms involved in the development of allergy and the role of immunomodulators in allergen recognition by innate cells (AU)

An unfolded variant of the major peanut allergen Ara h 2 with decreased anaphylactic potential.

BACKGROUND: Peanut allergy causes severe type 1 hypersensitivity reactions and conventional immunotherapy against peanut allergy is associated with a high risk of anaphylaxis. OBJECTIVE: Our current study reports proof of concept experiments on the safety of a stably denatured variant of the major peanut allergen Ara h 2 for immunotherapy. We determined the impact of structure loss of Ara h 2 on its IgE binding and basophil degranulation capacity, T cell reactivity as well as anaphylactic potential. METHODS: The secondary structure of untreated and reduced/alkylated Ara h 2 variants was determined by circular dichroism spectroscopy. We addressed human patient IgE binding to Ara h 2 by ELISA and Western blot experiments. RBL-SX38 cells were used to test the degranulation induced by untreated and reduced/alkylated Ara h 2. We assessed the anaphylactic potential of Ara h 2 variants by challenge of sensitized BALB/c mice. T cell reactivity was investigated using human Ara h 2-specific T cell lines and splenocytes isolated from sensitized mice. RESULTS: Reduction/alkylation of Ara h 2 caused a decrease in IgE binding capacity, basophil degranulation and anaphylactic potential in vivo. However, the human T cell response to reduced/alkylated and untreated Ara h 2 was comparable. Mouse splenocytes showed higher metabolic activity upon stimulation with reduced/alkylated Ara h 2 and released similar IL-4, IL-13 and IFNγ levels upon treatment with either Ara h 2 variant. CONCLUSIONS AND CLINICAL RELEVANCE: Reduced/alkylated Ara h 2 might be a safer alternative than native Ara h 2 for immunotherapeutic treatment of peanut allergic patients.

Anaphylaxis to peanut in a patient predominantly sensitized to Ara h 6.

Diagnosis of peanut allergy has improved thanks to component-resolved diagnostics. Peanut allergen component Ara h 2 is considered to indicate true peanut allergy. The component Ara h 6 is structurally similar to Ara h 2, but the diagnostic value of analyzing IgE antibodies to Ara h 6 is unclear. A boy sensitized (≥0.35 kU(A)/l) to Ara h 8 but not to Ara h 1, Ara h 2 and Ara h 3 was challenged with peanut and developed grade II anaphylaxis. In serum collected at the time of challenge a doubling of IgE to the peanut allergen extract was observed compared to allergy testing 9 months earlier. In contrast, IgE levels to Ara h 1, Ara h 2, Ara h 3 and to Ara h 8 were rather unchanged. After another 2 months, Ara h 6 was analyzed and revealed a level of 24 kU(A)/l whilst Ara h 2 was 0.12 kU(A)/l. We suggest that IgE sensitization to Ara h 6 caused the reaction and conclude that analyses of IgE levels to peanut and peanut components should be performed in connection with a challenge. Furthermore, levels to Ara h 2 below 0.35 kU(A)/l may still indicate a risk of severe reaction at the time of challenge since in rare cases, Ara h 6 IgE antibodies may be present without occurrence of IgE antibodies to Ara h 2.

One-step multiplex PCR method for the determination of pecan and Brazil nut allergens in food products.

BACKGROUND: A one-step polymerase chain reaction (PCR) method for the simultaneous detection of the major allergens of pecan and Brazil nuts was developed. Primer pairs for the amplification of partial sequences of genes encoding the allergens were designed and tested for their specificity on a range of food components. RESULTS: The targeted amplicon size was 173 bp of Ber e 1 gene of Brazil nuts and 72 bp of vicilin-like seed storage protein gene in pecan nuts. The primer pair detecting the noncoding region of the chloroplast DNA was used as the internal control of amplification. The intrinsic detection limit of the PCR method was 100 pg mL(-1) pecan or Brazil nuts DNA. The practical detection limit was 0.1% w/w (1 g kg(-1)). The method was applied for the investigation of 63 samples with the declaration of pecans, Brazil nuts, other different nut species or nuts generally. In 15 food samples pecans and Brazil nuts allergens were identified in the conformity with the food declaration. CONCLUSION: The presented multiplex PCR method is specific enough and can be used as a fast approach for the detection of major allergens of pecan or Brazil nuts in food.