The immunofluorescent findings on sixty-four specimens of lung obtained by biopsy or at autopsy have been reported. In thirty-three cases of fibrosing aiveolitis, evidence of antibody formation in plasma cells or germinal follicles was found in seventeen. Occasional macrophages containing both immunoglobulin and complement were found in seven. In six instances evidence of antibody and complement deposited in alveolar capillaries was found. In all of these circulating antinuclear factor, usually in moderately high titre was found. These findings have been compared with those seen in a small number of cases with extrinsic allergic alveolitis, asbestosis and other chronic lung disease.
It is suggested that immune-complex deposition may be related to the immunopathogenesis of some, albeit a minority, cases of fibrosing alveolitis.