Identification of the IgE-binding epitope in omega-5 gliadin, a major allergen in wheat-dependent exercise-induced anaphylaxis.
Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a severe IgE-mediated allergic reaction provoked by the combination of wheat-ingestion with intensive physical exercise over the next few hours. Among wheat proteins, omega-5 gliadin, which is one of the components of fast omega-gliadin, has been reported as a major allergen in the anaphylaxis. In this study, we detected IgE-binding epitopes within the primary sequence of omega-5 gliadin using arrays of overlapping peptides synthesized on derivatized cellulose membranes. Sera from four patients with WDEIA having specific IgE to the fast omega-gliadin were used to probe the membrane. Seven epitopes, QQIPQQQ, QQLPQQQ, QQFPQQQ, QQSPEQQ, QQSPQQQ, QQYPQQQ, and PYPP, were detected within the primary sequence of omega-5 gliadin. By using sera of 15 patients, 4 of them, QQIPQQQ, QQFPQQQ, QQSPEQQ, and QQSPQQQ, were found to be dominant epitopes. Mutational analysis of the QQIPQQQ and QQFPQQQ indicated that amino acids at positions Gln(1), Pro(4), Gln(5), Gln(6), and Gln(7) were critical for IgE binding. These results will provide a useful tool for developing safer wheat products in addition to diagnostic and immunotherapy techniques for WDEIA.
Matsuo
Hiroaki
H
Department of Dermatology, School of Medicine, Shimane University, 89-1 Enya-cho, Izumo, Shimane 693-8501, Japan. hmatsuo@med.shimane-u.ac.jp
Morita
Eishin
E
Tatham
Arthur Sydney
AS
Morimoto
Kenichi
K
Horikawa
Tatsuya
T
Osuna
Hiroyuki
H
Ikezawa
Zenro
Z
Kaneko
Sakae
S
Kohno
Kunie
K
Dekio
Satoshi
S
D000485:Allergens / Q000737:chemistry*; D000595:Amino Acid Sequence; D000707:Anaphylaxis / Q000276:immunology*; D052179:Antigens, Plant; D015153:Blotting, Western; D004252:DNA Mutational Analysis; D000939:Epitopes / Q000737:chemistry*; D015444:Exercise; D005903:Gliadin / Q000737:chemistry*; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000378:metabolism*; D021182:Wheat Hypersensitivity
D000485:Allergens; D052179:Antigens, Plant; D000939:Epitopes; D010455:Peptides; C475180:omega-5 gliadin, wheat; D007073:Immunoglobulin E; D005903:Gliadin