The pathogenesis of experimental pulmonary aspergillosis in normal and cortisone-treated rats.

Normal outbred adult Wistar rats were resistant to infection with intratracheally administered viable spores of Aspergillus fumigatus although although they developed a subacute interestitial pneumonia. While the lesions were more severe in animals immune suppressed with Azathioprine (immuran) there was no evidence of hyphal growth in the pulmonary tissue. Significant histological involvement was found only in those animals receiving repeared subcutaneous injections of cortisone and multiple intratracheal injections of spores. Granulomatous lesions were scattered throughout the parenchyma of the lung, and many eroded the walls of adjoining bronchioles permitting entry of the material in the necrotic centre of the granuloma into the lumen of the bronchiole.