Partially purified cotton bract extracts were shown previously to contain non-charged, low molecular weight (<1,000 daltons), water soluble components characterized by UV absorbance at 225nm and a broad triple peak at 262nm and fluorescence at 430nm. Neither lacinilene, tannin, nor endotoxin is present. These bract extracts cause acute airway constriction in humans. They are also chemotactic for human polyinorphonuclear leukocytes. Both activities are reported to be part of the respose mechanism of mill workers to cotton dust. Purified bract extracts were fractionated on columns of silica and C18 bonded phase. Airway constricting activity was found to elute with polar solvents. The airway constricting activity and chemotactic activity of each fraction was compared to determine if a correlation exists between the two activities suggesting a common causative agent. The two activities were found to be present in the same fraction. This fraction also fluoresced at 430nm but its UV spectrum was somewhat changed from that of the whole extract, the 262nm shoulder was shifted to 258nm and had less triplet-like character.