Specific depletion of the house dust mite allergen Der p 1 by cereal flour prolamins

Background: Quantitation of Der 1 and Der 2 in dust samples by specific monoclonal antibodies is a method used increasingly to evaluate mite allergen exposure. The level of Der 1 has been proposed as a risk factor for sensitization. Aim: We report a drastic decrease in the Der 1/Der 2 ratio when dust samples are collected in bakeries. Methods: Wheat flour and purified mites were extracted simultaneously; levels of Der p 1 and Der p 2 and cysteine protease activity were determined by ELISA and inhibition experiments. Results: High titers of Der 2, but only trace amounts of Der p 1, were detected in dust samples collected from bakeries. Both the level and proteolytic activity of Der p 1 appeared greatly decreased when mites and wheat flour were coextracted. Conclusions: Group 1 protein was found to be masked by flour components, resulting in an underestimation of the mite content in bakery dust. This problem was not found for group 2 allergen.