[Immunologic response to microorganisms from a polluted ventilation system in a working environment]

Authors point out the morbidity of employees working in ventilation systems contaminated with various microorganisms. They analysed 96 workers exposed to air conditioning system (Group A), and 71 workers (Group B) breathing normal ambient air. The workers of both groups were subjected clinically by functionally and immunologically. Preparation of antigens "MMM" (Monday morning miseries) was used as an original method by Ajello et al. for producing antigens from systemic mycotic agents and subsequently modified. The aim of the present study is to evaluate the possibility of using ELISA in clinical practice for respiratory allergy diagnosis, and especially Hypersensitivity pneumonitis. Atopic status was determined by skin prick tests with common airborne allergens including Dermatophagoides pteronyssinus, ragweed, grasses and Aspergillus fumigatus., by Enzygnost--IgE (Behringwerke AG, Marburg) and for specific IgE by RAST technique (Pharmacia, Uppsala). The skin prick tests were performed with "MMM"-antigens. PEFR (Peak Expiratory Flow-Rate) was measured by using a Wright's peak flow meter. PEFR was recorded on Monday (first day at work) and Friday (the end of the working week). Measured values of PEFR in both groups of employees from Monday to Friday were elaborated by the Wilcoxon test.

Culture of scrapings from air conditioning vents were obtained and water from the humidifier system also cultured. They were grown: T. vulgaris, Aspergillus fumigatus, Thermoactinomyces vulgaris and others. Results of questionnaires, clinical evaluation and diagnostical procedures in employees of Group A and B are as follows: Thirty eight workers in Group A had a positive clinical history of "Monday illness". In the symptomatic Group A we found in 8 cases abnormal chest roentgenogram. Further, there was no correlation between the presence of antibodies (ELISA) against MMM and pulmonary function abnormalities, as measured by either spirometry or DLCO. Further, we found good agreement between ELISA and prick test results with antigen MMM. Wilcoxon test showed a statistically significant difference between the two groups (0.01). The median or central value of PEFR reduction in Group A is 10.23 per cent, and in Group B 1.49 per cent. A 30 per cent reduction of PEFR was observed in 5.21 per cent of subjects in Group A. Exposure to ventilation systems contaminated with Thermophilic actinomyces may be responsible for increased morbidity and reduced performance of employees working in air conditioning systems. Particularly the main filter should be checked regularly. Moreover, regular microbiologic examinations of dust and water from air preventing chronic obstructive lung diseases in employees working in areas served by contaminated air conditioning systems.