Pathogenesis of extrinsic allergic alveolitis and pulmonary fibrosis induced by streptomyces thermohygroscopicus.

There were 48 strains of thermophilic actinomyces isolated from the specimens of mouldy hay and sputum of the patients suffering from farmer's lung (FL). Streptomyces thermohygroscopicus (STHs), one strain of them, was used for this investigation. The microorganisms were injected into the lungs of rabbits and rats by thyrocrico- or tracheocentesis. The results showed that the pathological changes in the lungs including macrophage alveolitis, granuloma formation and diffuse interstitial were similar to that induced by other thermophilic actinomyces. IgG and C3 deposition in the lesions were also observed by immunofluorescence examination. Specific immunocomplexes in the sera of some animals were detected by ELISA with the STH-antisera. The results suggested that STHs was possibly one of the pathogens responsible for FL in China's countryside.