Rye flour induces a stronger early bronchial response than wheat flour in occupational asthma

Background: Our aims were to compare the doses of wheat and rye flour that induce early bronchial responses in occupationally exposed asthmatic subjects and to assess the effects of the dose of inhaled flour, the duration of exposure and the dose rate. Methods: Ten patients underwent tests with lactose, wheat flour and rye flour. We compared the decrease in forced expiratory volume in 1 s (FEV1) observed during the challenge with flour and with lactose. We also calculated the amount of flour that was instantaneously active. Results: Seven subjects had significantly decreased FEV1 values following exposure to wheat and rye flour and two subjects only did so for rye flour. The provocative dose (PD, dose required to reduce FEV1 by 15%) of rye was lower than that of wheat flour (geometric mean; PD15 rye: 95 mug; wheat: 368 mug). The calculated doses of rye and wheat flour were better correlated with the change in FEV1 than were the cumulative doses. Conclusion: The bronchial response was greater with rye than with wheat flour. The response was related to the dose of allergen inhaled and to the dose rate.