Immunohistochemical identification of Aspergillus fumigatus in farmer's lung.

Fragments of fungi in a granuloma were demonstrated in lung biopsy specimens of two patients with farmer's lung by using an avidin-biotin-complex method with non-conjugated rabbit antiserum to Aspergillus fumigatus. Our findings suggest that the type IV or cell-mediated immunity at least partly explains the pathogenesis of farmer's lung.