Major wheat and rye allergens associated with baker's asthma have been identified as specific inhibitors of Dermatophagoides pteronyssinus alpha-amylase (Der p 4). the most active inhibitors were the wheat tetrameric one and the rye dimeric RDAI-1. these data suggest that interaction between mite and cereal allergens (alpha-amylase/inhibitor complexes) might occur in house-dust-mite-infected flours. In contrast to the strong inhibition of the d. pteronyssinus enzyme by the wheat and rye inhibitors, the amylases from D. farinae, Lepidoglyphus destructor, and Tyrophagus putrescentiae were much less affected. Moreover, the D. pteronyssinus amylase showed higher pH optimum (6.5 versus 5.0) and activity level (2-6 times/mg of protein in whole-mite extracts) than those from the three other mite species.