An immunofluorescent study of lung, hilar lymph nodes and spleen in a series of autopsied cases.

Direct immunofluorescence reactions were performed with conjugated antihuman IgA, IgG, and IgM sera on bronchi, lung, lymph nodes and spleen, sampled at 12-72 h after death in a series of 20 cases submitted to autopsy. The IgA cells were preponderent in the lung where they concentrate preferentially in the bronchial tree, whereas the IgG and IgM cells were found in a relative higher proportion in the pulmonary parenchyma. The most intense lung immunofluorescence reactions were identified in pneumonias; in relation of these types they acquire distinct aspects: a bronchio-peribronchial disposition in bronchopneumonia and an interstitial-perivascular one in plasma cell pneumonitis. The lymph nodes and spleen of the same cases presented mostly IgG cells, but also, in a smaller amount, IgA and IgM plasma cells.