REVIEW Allergens in wheat and related cereals A. S. Tatham à and P. R. Shewry w à Cardiff School of Health Sciences, University of Wales Institute Cardiff, Western Avenue, Cardiff CF5 2YB, UK and w Centre for Crop Genetic Improvement, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Clinical and Experimental Allergy Correspondence: A. S. Tatham, Cardiff School of Health Sciences, University of Wales Institute Cardiff, Western Avenue, Cardiff CF5 2YB, UK. E-mail: atatham@uwic.ac.uk Cite this as: A. S. Tatham and P. R. Shewry, Clinical and Experimental Allergy , 2008 (38) 1712–1726. Summary Wheat is one of the major crops grown, processed and consumed by humankind and is associated with both intolerances (notably coeliac disease) and allergies. Two types of allergy are particularly well characterized. The first is bakers’ asthma, which results from the inhalation of flour and dust during grain processing. Although a number of wheat proteins have been shown to bind IgE from patients with bakers’ asthma, there is no doubt a well-characterized group of inhibitors of a-amylase (also called chloroform methanol soluble, or CM, proteins) are the major components responsible for this syndrome. The second well-characterized form of allergy to wheat proteins is wheat-dependent exercise-induced anaphylaxis (WDEIA), with the o 5 -gliadins (part of the gluten protein fraction) being the major group of proteins which are responsible. Other forms of food allergy have also been reported, with the proteins responsible including gluten proteins, CM proteins and non-specific lipid transfer proteins. Processing of wheat and of related cereals (barley and rye, which may contain related allergens) may lead to decreased allergenicity while genetic engineering technology offers opportunities to eliminate allergens by suppressing gene expression. Keywords allergy, cereals, wheat Submitted 7 December 2007; revised 16 July 2008; accepted 30 July 2008 Introduction World agriculture is dominated by three cereal crops – wheat, rice and maize – which each yield about 600 million tonnes per year. Of these, wheat is the most widely grown, from Scandinavia and Russia in the north to Argentina in the south, including higher areas in the tropics. It is immensely diverse, with over 25 000 different cultivars having been produced by plant breeders world- wide [1]. Much of the world production of wheat is con- sumed by humans, after processing to bread and other baked goods, pasta and noodles and, in the Middle East and North Africa, bulgar and couscous. In addition, the wide availability of wheat flour and the functional proper- ties of wheat starch and gluten proteins mean that it is widely used as an ingredient in food processing. In fact, a brief inspection of processed foods currently on sale in Western Europe and North America shows that wheat flour, proteins or starch are present in a surprisingly high percentage, highlighting the problem for those suffering from dietary allergy or intolerance to wheat. In addition, many workers in the milling, baking and food processing industries are exposed to wheat flour in the atmosphere, raising the risk of respiratory allergy. Much of the research on adverse reactions to wheat has focused on respiratory allergy (bakers’ asthma) which is one of the most important occupational allergies in many countries including UK (see below) and on coeliac disease, a form of gluten intolerance which is estimated to affect about 1% of the population in Europe, North and South America, North Africa and the Indian subcontinent [2]. Dietary allergy to wheat is probably less widespread in the general population but may affect 1% of children [3] and in its extreme form may lead to anaphylaxis and death. The proteins which are responsible for dietary allergy in wheat are also less clearly defined than those contributing to bakers’ asthma but recent studies indicate that there are intriguing similarities and differences between the two conditions. The present article therefore reviews our current knowledge of the protein responsible for dietary doi: 10.1111/j.1365-2222.2008.03101.x Clinical and Experimental Allergy, 38, 1712–1726  c 2008 The Authors Journal compilation  c 2008 Blackwell Publishing Ltd