A rye flour protein of about 13.5 kDa, as well as its barley homologue, have been isolated. The rye component was recognized in vitro by IgE of allergic patients and provoked positive responses in 15 out of 21 baker's asthma patients (71%) when skin prick tests were performed. Its barley homologue showed no detectable in vitro reactivity and caused positive responses in only one-third of patients. Although no inhibitory activity against different α-amylases or trypsin was found for these two proteins, their N-terminal sequencing revealed considerable similarity to several members of the cereal α-amylase/trypsin inhibitor family.
