Quantification of the dose of inhaled flour: relation with nonspecific bronchial and immunological reactivities

The aim of this study was to investigate the relationship between specific bronchial reactivity and respective nonspecific bronchial and immunological reactivities. Twenty-one patients underwent bronchial challenges with lactose and flour, The aerosol of particles was generated by a computer-controlled aerasolizer , Specific bronchial challenge results were expressed as the provocative do se of flour (PDf) that caused a 20% or 15% decrease in the forced expirator y volume in one second (FEV1). For each subject, the decrease in FEV1 obser ved during the challenge with pour was compared with the calculated lower l imit of the 99.7% confidence interval for the lactose challenge. The subjec ts also underwent a nonspecific challenge with methacholine and a measureme nt of the specific immunoglobulin E against wheat. The inhalation of lactose did not significantly affect FEV1. Nine subjects had high reactivity to wheat flour with a PDf20 <400 mu g. Five subjects ha d intermediate reactivity: FEV1 fell by <20% but by significantly more than that in the test with lactose. For 7 subjects, there was no significant ch ange in FEV1 for inhaled doses of flour over 1390 mu g. The results for spe cific bronchial challenge were significantly correlated with those for the methacholine test (p<0.02). positive shin tests and specific immunoglobulin E against wheat were observed more frequently in the high reactivity group . Specific bronchial challenge can be performed safely to establish precise d ose-response curves. The provocative dose of flour causing a 20% decrease i n forced expiratory volume in one second is useful for evaluating the degre e of specific reactivity but is not suitable in cases of intermediate react ivity in which comparison with the lactose test is necessary. Specific reac tivity is probably a function of immunological and nonspecific bronchial re activities.