Identification of a New Natural Ara h 6 Isoform and of Its Proteolytic Product as Major Allergens in Peanut

• DOI: 10.1021/jf071424g
• Publication Date: 2007-10-20T04:26:49Z
• Authors: H. Bernard; L. Mondoulet; M. F. Drumare; E. Paty; P. Scheinmann; R. Thaï; J. M. Wal
• Keywords: Male; 0301 basic medicine; [CHIM.ANAL] Chemical Sciences/Analytical chemistry; Molecular Biology/Biochemistry [q-bio.BM]; Molecular Sequence Data; Immunoenzyme Techniques; 03 medical and health sciences; [CHIM.ANAL]Chemical Sciences/Analytical chemistry; Humans; Protein Isoforms; Peanut Hypersensitivity; Trypsin; Amino Acid Sequence; [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM]; [SDV.IMM.ALL]Life Sciences [q-bio]/Immunology/Allergology; Child; [SDV.BBM.BC] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM]; Skin Tests; 2. Zero hunger; Allergens; Antigens, Plant; Immunoglobulin E; Peptide Fragments; [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry; Female; [SDV.IMM.ALL] Life Sciences [q-bio]/Immunology/Allergology; 2S Albumins, Plant

Numerous food allergens of plant origin belong to the 2S albumin family, including peanut Ara h 2. In addition to Ara h 2, several other conglutins related to 2S albumins are present in peanut seeds. We evaluated the allergenicity of different peanut conglutins as compared with Ara h 2. Several conglutins were isolated from the kernel, i.e. Ara h 2, a new isoform of Ara h 6 and its derived product, which is likely to be naturally formed during seed processing. Enzyme allergosorbent tests performed on sera of peanut allergic patients showed that more than 94% of 47 analyzed patients had positive IgE responses to Ara h 6 isoform and to its degradation product. Skin prick tests with the new isoform of Ara h 6 led to a positive response in seven out of the eight tested patients. Both enzyme allergosorbent tests and skin prick tests showed that the reactivity of Ara h 6 was similar to, or even higher than, that of Ara h 2, suggesting that the present isoform of Ara h 6 is as allergenic as Ara h 2. In addition the IgE response to the plant processed (i.e., hydrolyzed) Ara h 6 new isoform is equivalent to the IgE response to the native isoform. The IgE immunoreactivity is mostly abrogated by chemical reduction and denaturation of Ara h 6 isoforms, which underlined the importance of tertiary structure in Ara h 6 immunoreactivity. These results, and particularly the high correlation between anti-Ara h 2 and anti-Ara h 6 IgE responses, emphasise the major role of 2S albumins in peanut allergenicity.