The acute airway constrictor response of volunteers to inhaled cotton bract extracts is similar to that of workers in cotton textile mills. Those volunteers who respond do so with a mean decrease in the flow rate, MEF40%(P) value of 30% and a corresponding decrease of 8% for the FEV(1.0) value following inhalation of a crude aqueous extract of bracts. Aqueous crude extracts of cotton dust including the "Reference" dust supplied by Cotton Incorporated induce similar decreases in lung function when inhaled by these volunteers.

Purified bract extracts were prepared which retain the ability to induce airway constriction in humans and are essentially free of endotoxin (less than 0.001 µg/ml). These extracts are 10 mg/ml dry weight, 20% of which is glucose and amino groups are also present. Molecular weight membrane dialysis and size ex clusion HPLC of the purified extracts confirm earlier Sephadex G-10 experiments suggesting that the airway constricting agent(s) is a low molecular weight component of 1,000 or less. The airway constricting agent does not bind to anion or cation exchanger, C(18), or silica, but does bind to charcoal. Charcoal binds about one-half the dry weight and TLC shows this includes several fluorescent and ninhydrin position spots. These can be removed from the charcoal with phenol. Further characterization of these, including airway constricting activity, is planned.