J.-L. Malo

Exposure to a sensitizing occupational agent can cause a long-lasting increase in bronchial responsiveness to histamine in the absence of significant changes in airway caliber

A 58-year-old subject with a history of occupational asthma to red-cedar sawdust underwent specific inhalation challenges with this product. Significant increases in airway responsiveness to histamine (tenfold fall in PC20 FEV1) were documented 7 hours after exposure for 5 minutes to red cedar while baseline spirometry remained unchanged. A dual asthmatic reaction was induced during the following days by exposing the subject to red-cedar sawdust for 30 minutes and plicatic acid for 7 minutes. After recovery of PC20, the subject was reexposed to plicatic acid for 15 and 30 seconds on 2 consecutive days. No significant changes in FEV1, forced vital capacity, and residual volume were demonstrated in the following 8 hours, although minimal changes in forced expiratory flow rate between 25% and 75% of FVC were observed. PC20 dropped significantly and required 2 weeks to recover. This example illustrates that bronchial hyperresponsiveness to histamine can precede the changes in airway caliber after an antigen challenge. It also demonstrates that such changes can persist for up to 2 weeks after the challenge, even when no significant changes in FEV1 are induced.

Lower Airway Inflammation Assessed by Induced Sputum in a Cluster of Cases Suggestive of Organic Dust Toxic Syndrome

in a Cluster of Cases Suggestive of Organic Dust Toxic Syndrome R. Castano, J. L. Malo, C. Lemiere, M. Labrecque, A. Cartier; Hopital du Sacre-Coeur de Montreal, Montreal, PQ, CANADA. RATIONALE: To examine pulmonary responses and characterize airway inflammation in workers with respiratory symptoms suggestive of Organic Dust Toxic Syndrome (ODTS). METHODS: We assessed 14 workers of a large factory of sanitary napkins complaining of recurrent work-related cough, shortness of breath, phlegm production and fever with chills. All workers underwent specific inhalation challenges (SIC) for 2 to 4 hours with dust obtained from the floor next to the operating machines. All subjects had measurements of temperature, expiratory flows, white blood cell count (WBC), carbon monoxide diffusing capacity (DLCO) and induced sputum before and after exposure. RESULTS: Only one subject presented symptoms on exposure suggesting extrinsic allergic alveolitis (EAA) with increases in temperature (36.3 to 37.88C) and WBC (5.2 to 10.7 cells per cc) and a decrease in DLCO (23.3 to 18.4). After exposure only one subject had a significant decrease (26%) in forced expiratory volume in one second. In induced sputum 13 subjects had an increase in total cell counts (mean 55.3 10 c/ml; range 8.2-113.4) and 12 in neutrophils (mean 39%; range 20-92%). CONCLUSIONS: We have thus described workers with features of ODTS, EAA and asthma. We hypothesize that these conditions may be considered one syndrome with a wide spectrum of severity ranging from a less severe condition (ODTS) in one end of the spectrum to a more severe disease in the other (EAA). Results also support the use of induced sputum in the investigation of ODTS. The etiology of this syndrome in our workers is still unknown. Funding: Universite de Montreal