Time course of airway inflammation in occupational asthma induced by cobalt [Decorso dell'infiammazione delle vie aeree nell'asma professionale indotta da cobalto]

Abstract The case history refers to a subject who started to complain of asthma symptoms at work and at night after he had been exposed to cobalt dust in the press department of an abrasive production plant for one year. He was examined after 6 months of no exposure to cobalt. He had no history of previous asthma or atopy and never smoked. Patch test and prick test with cobalt chloride were negative. Baseline lung function was normal, but the patient exhibited bronchial hyperresponsiveness to methacholine, elevated exhaled NO levels (99 ppb) and sputum eosinophilia (6.6%). Specific bronchial challenge with cobalt dust induced a late asthmatic reaction with maximal fall in FEV1 of 33% 7 hours after exposure. Increase in exhaled NO was observed 24h after challenge, which was maximal at 48h and sustained up to 7 days. The percentages of sputum eosinophils substantially increased 24h (30%) and 7 days (21%) after challenge. In conclusion, the inflammatory response of the airways induced by exposure to cobalt is characterised by an increase of sputum eosinophils and exhaled NO that persists for several days after specific bronchial challenge with cobalt dust.