HYPERSENSITIVITY PNEUMONITIS ASSOCIATED WITH HOME ULTRASONIC HUMIDIFIERS

We describe five patients with hypersensitivity pneumonitis (HP) that was related to using home ultrasonic humidifiers. All patients had mic ronodular infiltrates on their chest radiograph, and their lung biopsy specimens revealed alveolitis with or without epithelioid cell granul omas. Challenge tests were performed on two patients with the humidifi er water and three patients using the humidifier. All patients tested exhibited a positive response. Tests for precipitating antibodies agai nst an extract of the humidifier water gave strongly positive reaction s in ah patients tested. Precipitins to Cephalosporium acremonium and Candida albicans were also present in all cases, whereas precipitins t o thermophilic actinomycetes were not detected. Although cultures of t he water grew a variety of fungal and bacterial organisms, thermophili c actinomycetes could not be detected. These findings suggest that the rmophilic organisms may not be the causative antigens of HP associated with ultrasonic humidifiers. All five patients had an increase in the bronchoalveolar lavage (BAL) lymphocytes that were predominantly CD4 lymphocytes. The T helper cell count (CD4) to suppressor T cell count (CD8) ratio was significantly higher than that observed in summer-typ e HP, and lower than that observed in bird fancier's lung, indicating that the phenotypes of the BAL lymphocytes may vary with the type of H P.