Immunologic cross-reactions of thermophilic actinomycetes isolated from home environments

Abstract

A thermophilic actinomycete was isolated from the furnace humidifier of a patient with hypersensitivity pneumonitis. Rabbit antiserum prepared by immunizing the animals with the spore extract of this microorganism showed a high titer of precipitins against the extract but failed to cross-react with antigens of other thermophilic actinomycete species, such as Thermoactinomyces vulgaris or Micropolyspora faeni. However, a number of sera from patients with farmer's lung or bagassosis contained precipitins against the thermophilic actinomycetes isolated from the furnace humidifier. These findings suggest that the thermophilic actinomycetes isolated from home environments may also be found in other surroundings and may belong to some less common or not yet identified species. Because of the lack of cross-reactivity among the individual thermophiles, patients suspected of having hypersensitivity pneumonitis due to inhalation of thermophilic actinomycetes should be tested for precipitins with the use of the microorganism isolated from their own environment.