Wheat flour peroxidase is a prominent allergen associated with baker's asthma

Background Putative wheat allergens with molecular sizes around 35 kDa have been repeatedly detected in immunoblots using sera from patients with baker's asthma. However, none of these allergens had been previously isolated. Objective To purify and characterize a major component of the 35 kDa allergenic band which seems to be present in flour from diploid, tetraploid (pasta) and hexaploid (bread) wheats. Methods Gel-filtration chromatography followed by RP-HPLC have allowed the purification of a new wheat allergen. Immunodetection with sera from allergic patients and with a specific serum for asparagine-linked complex glycans, as well as amino acid sequencing, were used to identify the isolated protein. Results A 36 kDa allergen has been purified from wheat flour. Its N-terminal and internal sequences, N-linked glycans, and enzymatic activity indicated that this allergen is a seed-specific peroxidase. Sera from six out of 10 patients hypersensitive to wheat flour displayed positive reactions when assayed against the purified dot-blotted allergen. Conclusion Seed-specific peroxidases from cereals (flours) seem to be important allergens in hypersensitive diseases associated with the manipulation of these plant materials. A new enzyme has thus been involved in IgE-mediated diseases.