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Pokoj S.,Paul Ehrlich Institute | Lauer I.,Paul Ehrlich Institute | Fotisch K.,Paul Ehrlich Institute | Himly M.,University of Salzburg | And 5 more authors.
Protein Expression and Purification

Non-specific lipid-transfer proteins (nsLTP) from food and pollen are clinically important allergens, especially in patients recruited from the Mediterranean area. For the use of recombinant nsLTPs in allergy diagnosis and preclinical allergy studies the preparation of nsLTPs in a properly folded and biologically active form is required. Using hazelnut nsLTP (Cor a 8) as a model allergen, heterologous over-expression in Escherichia coli and Pichia pastoris was compared. Recombinant Cor a 8 derived from E. coli and P. pastoris was purified by IMAC and SEC or ammonium sulphate precipitation followed by IEC and SEC, respectively. The recombinant proteins were characterized with regard to IgE-binding by immunoblotting and ELISA, structure by N-terminal sequencing, CD-spectroscopy and LS and to their biological activity using an in vitro basophil histamine release assay. Purification of hazelnut nsLTP from bacterial lysate under native conditions resulted in a low yield of Cor a 8. In addition, the preparation contained non-IgE-reactive aggregations besides the IgE-reactive monomer. In contrast, the yield of rCor a 8 produced in P. pastoris was approximately 270-fold higher and impurities with oligomers have not been detected. Purified monomeric Cor a 8 from bacteria and yeast showed similar IgE-antibody reactivity and secondary structures, and both were capable of inducing histamine release from basophils. In summary, P. pastoris is superior to E. coli as expression system for the production of large quantities of soluble, properly folded, and biologically active rCor a 8. © 2009 Elsevier Inc. All rights reserved. Source

Zheng Y.-W.,Research Asia Pacific | Li J.,Guangzhou Medical College | Lai X.-X.,Research Asia Pacific | Zhao D.-Y.,Nanjing Medical University | And 7 more authors.
Chinese Medical Journal

Background Allergen micro-arrays are powerful tools for screening of serum IgE-reactivity. In this study allergen micro-arrays were used to identify dominating IgE-binding allergens and cross-reactivity patterns among selected Chinese allergy patients. Methods The study was conducted using patient sera from the cities of Guangzhou, Nanjing, Chengdu and Shenyang. In total 100 sera with Dermatophagoides pteronyssinus (Der p) specific IgE-levels higher than 50 kU/L were selected for testing against 103 individual allergens. Results Among 100 selected patients, 95% showed IgE-reactivity towards house-dust mite allergens Dermatophagoides farinae (Der f) 1, Der f 2 and Der p 2 and 94% were IgE positive against Der p 1, and 60% of sera contained IgE reacting against allergen Euroglyphus maynei (Eur m) 2. IgE against cat allergen, Felisdomesticus (Fel d) 1, was seen in 20%. Only 2% showed specific IgE-reactivity to Der p 10, a panallergen belonging to the tropomyosin family. Serum IgE-reactivity towards other allergens was in general low. IgE-reactivity against pollen allergens showed geographic differences. Conclusions This study clearly confirms that group 1 and group 2 are major allergens of house dust mites. These selected house-dust mite allergy patients are close to being mono-sensitized. Der p 10 is not an important allergen for cross-reactivity. Specific IgE-sensitization towards pollen allergens is low in southern China compared to other regions. The prevalence of food and stinging insect allergens known to give rise to IgE-mediated cross-reactivity is 2% or less. Source

Magni C.,University of Milan | Ballabio C.,University of Milan | Restani P.,University of Milan | Fuggetta D.,University of Milan | And 6 more authors.
Annals of Allergy, Asthma and Immunology

Background Food allergy is becoming a major public health concern in recent times. Several sesame seed allergenic proteins have been identified. However, sensitization toward these proteins does not follow a common and unique pattern of clinical reactivity, as shown by the differential geographic recognition of single proteins. Objective To evaluate the sensitization profiles of 18 Italian individuals who experienced clinical symptoms after sesame seed consumption, including 4 anaphylactic reactions. Methods Using an in vitro approach, we adopted a 2-dimensional electrophoretic technique combined with immunoblotting analyses by using sera from 18 Italian sesame-allergic patients. Results We showed the prevalent and almost exclusive reactivity of the sesame 11S globulin. We shed light on the active role of the basic subunit of this globulin family. The limited accessibility of this polypeptide chain, unless the interchain disulphide bonds are cleaved, may be one of the reasons for its structural/functional stability and, thus, great potential for induction of IgE reactivity. Conclusions These results confirmed previous findings on the reactivity of the basic subunit of 11S globulin in various legume species. Moreover, this experimental approach proved to be useful for the noninvasive screening of specific reactivities in sensitized patients. © 2010 American College of Allergy, Asthma & Immunology. Source

Hochwallner H.,Medical University of Vienna | Schulmeister U.,Medical University of Vienna | Swoboda I.,Christian Doppler Laboratory | Focke-Tejkl M.,Christian Doppler Laboratory | And 17 more authors.
Journal of Allergy and Clinical Immunology

Background: α-Lactalbumin (α-La) is a major cow's milk (CM) allergen responsible for allergic reactions in infants. Objective: We performed molecular, structural, and immunologic characterization of α-La. Methods: Recombinant α-lactalbumin (rα-La) was expressed in Escherichia coli, purified to homogeneity, and characterized by means of mass spectrometry and circular dichroism, and its allergenic activity was studied by using microarray technology, as well as in a basophil histamine release assay. IgE epitope mapping was performed with synthetic peptides. Results: According to circular dichroism analysis, rα-La represented a folded protein with a high thermal stability and refolding capacity. rα-La reacted with IgE antibodies from 57.6% of patients with CM allergy (n = 66) and induced the strongest basophil degranulation with sera from patients with CM allergy who had exhibited gastrointestinal symptoms or severe systemic reactions on CM exposure. rα-La contained sequential and conformational IgE epitopes. Superposition of IgE-reactive peptides onto the 3-dimensional structure of α-La revealed a close vicinity of the N- and C-terminal peptides within a surface-exposed patch. Conclusions: rα-La can be used for the diagnosis of patients with severe allergic reactions to CM and serves as a paradigmatic tool for the development of therapeutic strategies for CM allergy. © 2010 American Academy of Allergy, Asthma & Immunology. Source

Hochwallner H.,Medical University of Vienna | Schulmeister U.,Medical University of Vienna | Swoboda I.,Christian Doppler Laboratory | Balic N.,Medical University of Vienna | And 14 more authors.
Clinical and Experimental Allergy

Background Cow's milk is one of the most common causes of food allergy affecting approximately 2.5% of infants in the first years of their life. However, only limited information regarding the allergenic activity of individual cow's milk allergens is available.Objective To analyse the frequency of IgE reactivity and to determine the allergenic activity of individual cow's milk allergens.Methods A nitrocellulose-based microarray, based on purified natural and recombinant cow's milk allergens was used to determine IgE reactivity profiles using sera from 78 cow's milk-sensitized individuals of varying ages. The allergenic activity of the individual allergens was tested using patients' sera for loading rat basophil leukaemia cells (RBL) expressing the α-chain of the human receptor FcεRI.Results Using the microarray and the RBL assay, cow's milk allergens were assessed for frequency of IgE recognition and allergenic activity. Moreover, the RBL assay allowed distinguishing individuals without or with mild clinical reactions from those with severe systemic or gastrointestinal symptoms as well as persons who grew out cow's milk allergy from those who did not.Conclusions Component-resolved testing using milk allergen microarrays and RBL assays seems to provide useful additional diagnostic information and may represent a basis for future forms of prophylactic and therapeutic strategies for cow's milk allergy. © 2010 Blackwell Publishing Ltd. Source

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