The non-specific lipid transfer protein, Ara h 9, is an important allergen in peanut

• Published in: Clinical and experimental allergy Vol. 39; no. 9; pp. 1427 - 1437
• Main Authors: Lauer, I., Dueringer, N., Pokoj, S., Rehm, S., Zoccatelli, G., Reese, G., Miguel-Moncin, M. S., Cistero-Bahima, A., Enrique, E., Lidholm, J., Vieths, S., Scheurer, S.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2009; Blackwell
• Subjects: Allergens - chemistry; Allergens - immunology; Allergens - pharmacology; Allergic diseases; Animals; Antigens, Plant - chemistry; Antigens, Plant - immunology; Antigens, Plant - pharmacology; Ara h 9; Arachis hypogaea; Basophils - immunology; Biological and medical sciences; Carrier Proteins - chemistry; Carrier Proteins - immunology; Carrier Proteins - pharmacology; Circular Dichroism; Digestive allergic diseases; Female; food allergy; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Glycoproteins - chemistry; Glycoproteins - immunology; Glycoproteins - pharmacology; Histamine - immunology; Humans; Immunoglobulin E - blood; Immunoglobulin E - immunology; Immunopathology; lipid transfer protein; Male; Medical sciences; peanut allergen; Peanut Hypersensitivity - blood; Peanut Hypersensitivity - immunology; Pichia pastoris; Plant Proteins - chemistry; Plant Proteins - immunology; Plant Proteins - pharmacology; Protein Isoforms - chemistry; Protein Isoforms - immunology; Protein Isoforms - pharmacology; Protein Structure, Secondary; Pru p 3; Prunus; Rabbits; Recombinant Proteins - chemistry; Recombinant Proteins - immunology; Recombinant Proteins - pharmacology; Spain; Structural Homology, Protein; Spain; Immunopathology; Food allergy; Peanut; Immunology; Ara h 9; Lipid transfer protein; peanut allergen; Digestive diseases; Pru p 3; Groundnut; Allergen
• ISSN: 0954-7894; 1365-2222; 1365-2222
• DOI: 10.1111/j.1365-2222.2009.03312.x

Summary Background Plant food allergy in the Mediterranean area is mainly caused by non‐specific lipid transfer proteins (nsLTP). The aim of this study was to characterize peanut nsLTP in comparison with peach nsLTP, Pru p 3, and assess its importance in peanut allergy. Methods Peanut‐allergic patients from Spain (n=32) were included on the basis of a positive case history and either a positive skin prick test or specific IgE to peanut. For comparison, sera of 41 peanut‐allergic subjects from outside the Mediterranean area were used. Natural Ara h 9 and two isoforms of recombinant Ara h 9, expressed in Pichia pastoris, were purified using a two‐step chromatographic procedure. Allergen characterization was carried out by N‐terminal sequencing, circular dichroism (CD) spectroscopy, immunoblotting, IgE inhibition tests and basophil histamine release assays. Results Compared with natural peanut nsLTP, the recombinant proteins could be purified in high amounts from yeast supernatant (45 mg/L). The identity of the proteins was verified by N‐terminal amino acid sequencing and with rabbit nsLTP‐specific antibodies. CD spectroscopy revealed similar secondary structures for all preparations and Pru p 3. The Ara h 9 isoforms showed 62–68% amino acid sequence identity with Pru p 3. IgE antibody reactivity to rAra h 9 was present in 29/32 Spanish and 6/41 non‐Mediterranean subjects. Recombinant Ara h 9 showed strong cross‐reactivity to nPru p 3 and similar IgE‐binding capacity as nAra h 9. The two Ara h 9 isoforms displayed similar IgE reactivity. In peanut‐allergic patients with concomitant peach allergy, Ara h 9 showed a weaker allergenic potency than Pru p 3 in histamine release assays. Conclusions Ara h 9 is a major allergen in peanut‐allergic patients from the Mediterranean area. Ara h 9 is capable of inducing histamine release from basophils, but to a lesser extent than Pru p 3.