Wheat omega-5 gliadin is a major allergen in children with immediate allergy to ingested wheat.
BACKGROUND
Sensitization to wheat by ingestion can lead to food allergy symptoms and wheat-dependent, exercise-induced anaphylaxis. Sensitization by inhalation causes bakers' asthma and rhinitis. Wheat allergens have been characterized at the molecular level in bakers' asthma and in wheat-dependent, exercise-induced anaphylaxis, in which omega-5 gliadin (Tri a 19) is a major allergen. However, little information is available regarding allergens responsible for hypersensitivity reactions to ingested wheat in children.


OBJECTIVE
The aim of this study was to examine whether children with allergy to ingested wheat have IgE antibodies to omega-5 gliadin.


METHODS
Sera were obtained from 40 children (mean age, 2.5 years; range, 0.7-8.2 years) with suspected wheat allergy who presented with atopic dermatitis and/or gastrointestinal and/or respiratory symptoms. Wheat allergy was diagnosed with open or double-blinded, placebo-controlled oral wheat challenge. Wheat omega-5 gliadin was purified by reversed-phase chromatography, and serum IgE antibodies to omega-5 gliadin were measured by means of ELISA. In vivo reactivity was studied by skin prick testing. Control sera were obtained from 22 children with no evidence of food allergies.


RESULTS
In oral wheat challenge, 19 children (48%) reacted with immediate and 8 children (20%) with delayed hypersensitivity symptoms. Sixteen (84%) of the children with immediate symptoms had IgE antibodies to purified omega-5 gliadin in ELISA. In contrast, IgE antibodies to omega-5 gliadin were not detected in any of the children with delayed or negative challenge test results or in the control children. The diagnostic specificity and positive predictive value of omega-5 gliadin ELISA were each 100% for immediate challenge reactions. Skin prick testing with omega-5 gliadin was positive in 6 of 7 children with immediate challenge symptoms and negative in 2 children with delayed challenge symptoms.


CONCLUSIONS
The results of this study show that omega-5 gliadin is a significant allergen in young children with immediate allergic reactions to ingested wheat. IgE testing with omega-5 gliadin could be used to reduce the need for oral wheat challenges in children.
Palosuo
K
K
Department of Dermatology, University of Helsinki and Hospital for Skin and Allergic Diseases, Helsinki, Finland.
Varjonen
E
E
Kekki
O M
OM
Klemola
T
T
Kalkkinen
N
N
Alenius
H
H
Reunala
T
T
D000485:Allergens / Q000276:immunology*; D000906:Antibodies / Q000097:blood; D002648:Child; D002675:Child, Preschool; D005260:Female; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology*; D005903:Gliadin / Q000276:immunology*; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology; D006969:Hypersensitivity, Immediate / Q000209:etiology / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D012882:Skin Tests; D014908:Triticum / Q000009:adverse effects*
D000485:Allergens; D000906:Antibodies; D007073:Immunoglobulin E; D005903:Gliadin