Immunofluorescence studies of lung biopsy tissue

Thirty specimens of lung obtained by Abram's needle biopsy were examined using direct immunofluorescence. In 2 cases of Goodpasture's syndrome, linear deposits of IgG were demonstrated in alveolar walls. Diffuse deposits of IgG were found in the alveolar spaces of one patient with pigeon fancier's lung. Two subjects with cryptogenic fibrosing alveolitis had dense granular deposits of IgG in alveolar walls. Amorphous deposits of IgG were found in the pulmonary interstitium of a patient with desquamative interstitial pneumonitis. The small proportion of positive results obtained may reflect either the lack of a humoral immune background in the pathogeneses or only a fleeting involvement of humoral immunologic processes in each of the diseases studied. However, a small percentage of patients with diffuse interstitial disease do have antibody deposits demonstrable on small needle biopsy specimens. These require further investigation and may serve to define special groups. Various artifacts that were encountered led to difficulties in interpretation and these should be considered in reporting immunofluorescence studies of lung tissue. These included autofluorescence and nonspecific staining of connective tissue and cells. Nonspecific staining of eosinophils occurred frequently. The possible misinterpretation of artifacts as positive results is illustrated.