Purified Wheat Gliadin Proteins as Immunoglobulin E Binding Factors in Wheat Mediated Allergies

Abstract

Some wheat gliadin proteins are strong allergens that may cause various symptoms of food allergies and baker’s asthma. The most immunoreactive ω-5 gliadin fractions are the main allergens in wheat dependent exercise induced anaphylaxis (WDEIA). While the allergenicity of ω-5 is quite well understood, knowledge about α, β, γ and ω-1.2 gliadins is much more scanty. This study examines allergenic properties of other fractions as compared to ω-5. Gliadins were extracted from flour of winter wheat (Triticum aestivum L.) cultivar Ostka strzelecka. Purified samples representing proteins belonging to α, β, γ, ω-1.2 and ω-5 classes were isolated using preparative gel electrophoresis. Immuno-reactivity and allergenic properties of these proteins were analyzed by ELISA using sera from allergic patients with elevated sIgE (> 2KU/L), and by skin prick test (SPT). ELISA showed that ω-5 and ω-1.2 differed considerabely from α-, β- and γ-gliadins in respect of immunoreactivity. Responses of both ω-gliadins were almost twice as high as for other fractions. Significant differences were also observed among individual ω-gliadin fractions as evidenced by ANOVA. SPT showed that patient with symptoms of baker’s asthma and WDEIA had a positive results to all gliadins tested. Another patient with baker’s asthma (but not WDEIA) reacted positively only to ω-5 gliadins. In two patients with skin allergy SPT were negative with all analyzed proteins. Results show ω-1.2 gliadins to be almost as immunorective as ω-5. The α-, β- and γ-gliadins also recognize specific IgE antibodies, but their binding capacity is only about half that of ω-fractions. This kind of immunoreactivity could still be important since a cumulative effect of individual fractions may intensify disease symptoms in allergic patients

Antibody reactivity in patients with IgE-mediated wheat allergy to various subunits and fractions of gluten and non-gluten proteins from ω-gliadin-free wheat genotypes

“…The analyzed wheat hybrids were immuno-positive for a number of bands representing α, β, γ gliadins, LMW glutenins and NGP. These results have confirmed the immunoreactivity of α, β and γ gliadins, previously reported in our study that tested purified gliadin fractions by ELISA [28]. The current work is also consistent with the results obtained by other authors who reported allergenicity of α, β and γ gliadins in atopic dermatitis, and LMW glutenins in baker's asthma [20,29,30].…”

Null Alleles in Gliadin Coding Loci and Wheat Allergenic Properties

“…The highest decrease of immunoreactivity was observed in GDL lacking the ω-5 gliadin band confirming the highest allergenicity and immunodominant character of ω gliadins in allergies to wheat, especially ω-5 fractions that may trigger WDEIA [21,22]. However, decrease of IgE binding with GDL of reduced number of β fractions confirms our previous results on immunoreactivity of individual, purified gliadins indicating that other gliadin groups (besides the ω gliadins) may also share allergenicity of the protein complex [23].…”

Proteomic analysis of wheat α/A- and β-gliadins

“…Sixty aliquots of 7 ml containing gliadin fractions were collected beginning 5 h after the start of electrophoresis using pH 3.1 aluminum lactate buffer as eluent. The separation was completed 12 h after the onset of fraction collection (Bernardin et al 1967;Waga & Zientarski 2007;Waga et al 2011).…”

“…They are one of the most complex and polymorphic protein groups in the plant kingdom. Gliadins of a single wheat genotype are composed of hundreds of polypeptides controlled by six complex loci on chromosomes belonging to the 1 st and 6 th homology groups (1A, 1B, 1D, 6A, 6B, and 6D) of the hexaploid wheat genome (Triticum aestivum L.) (Payne 1987;Waga et al 2011). Particular loci comprise from several to several hundred closely linked genes which are inherited as clusters.…”

“…In both analytical and preparative applications, A-PAGE is the basic method of gliadin identification. Based on A-PAGE results, the gliadin complex extracted from one wheat genotype may be separated into dozens of protein fractions (Waga & Zientarski 2007;Waga et al 2011). Proteomic analysis, developed in the last two decades, greatly contributed to the identification of gliadins and research into gliadin activity in celiac disease.…”