Hypersensitivity pneumonitis and metalworking fluids contaminated by mycobacteria.

Metalworking fluids (MWF) are responsible for hypersensitivity pneumonitis (HP). The aim of the present study was to identify the antigen (Ag) responsible for MWF-associated HP, and to optimise serological diagnosis by definition of a threshold allowing discrimination between HP patients and asymptomatic exposed workers. 13 patients, who were workers at a car engine manufacturing plant, were suspected of MWF-associated HP. Microbial analysis of 83 used MWFs was carried out. Sera from 13 MWF-associated HP patients, 12 asymptomatic exposed workers and 18 healthy unexposed controls were tested to determine their immunological responses to three Ags, including Mycobacterium immunogenum. M. immunogenum was identified in 40% of used fluids by culture and confirmed by DNA sequencing. The threshold for differentiating MWF-associated HP patients from asymptomatic exposed workers was five arcs of precipitation (sensitivity 77% and specificity 92%), as determined by electrosyneresis (ES). Using ELISA methods with protein extract from M. immunogenum, a threshold leading to 92% sensitivity and 100% specificity was established. The detection of specific antibodies against M. immunogenum Ag at high levels in case sera suggests that M. immunogenum-contaminated MWF is responsible for MWF-associated HP. To discriminate MWF-associated HP patients from asymptomatic exposed workers, we suggest a five-arc threshold for ES and a 1.6-AU threshold for ELISA methods.

Recognition and progression of coal workers' pneumoconiosis in the collieries of northern France.

In France, both active and retired coal miners take part in medical surveillance programs. Those compensated for pneumoconiosis are registered and receive annual chest X-rays and regular lung function assessments. A longitudinal study was done among 2719 pneumoconiotics from the Nord-Pas de Calais region Compensation Register, who received first compensation between 1942 and 1987 to study progression of CSWP. Chest radiographs taken at time of compensation and in 1987 were examined by three independent readers. There was a change over time in the characteristics of pneumoconiosis at the time of first compensation toward a low profusion of irregular opacities. In the period from 1982 to 1987, 645 pneumoconiotics developed progressive massive fibrosis (PMF). The occurrence of PMF was related to the date of compensation and the profusion of small opacities at detection (after controlling for time to follow-up). Two profiles for changes in coal workers' simple pneumoconiosis (CWSP) were observed: the first in the group of subjects with mild pneumoconiosis at compensation, who did not reach category 2 at follow-up and had a low attack rate of PMF; and the second in the group of those compensated for category 1/2 pneumoconiosis or higher, who reached severe CWSP and had a twofold attack rate for PMF at follow-up. The changes observed in the characteristics of pneumoconiosis at first compensation between 1942 and 1987 suggest a lessening of disease severity.