Serial changes in lung injury produced by preformed immune complexes

A previous study demonstrated increased levels of C5a des Arg and increased numbers of polymorphonuclear cells (PMNs) in bronchoalveolar lavage (BAL) fluids of acutely ill patients with summer type hypersensitivity pneumonitis (HP), suggesting the role of immune complexes (IC) in the early stage of HP. The present study was undertaken to compare the BAL findings in patients with acute HP and in animals which were injected intratracheally with preformed IC and to determine the correlation between the sequential BAL findings and the serial histology in animals. The results indicated that total cells recovered by BAL increased up to 24 hours. However, the most striking observation was that the increased number and percentage of PMNs in BAL cells shortly after the intratracheal injection, which the number of macrophages in BAL cells tended to be high, the increase was not statistically significant. Histological examinations revealed peribronchial and intraalveolar infiltration with PMNs at the early stage when intraalveolar infiltration were predominant, and the latest lesions consisted of infiltration with mononuclear cells in the alveolar walls. Furthermore, the cellular findings of BAL cells reflected the histological findings in involved lungs. The present study demonstrated that the sequential BAL changes of acutely ill patients with HP were similar to those of IC-injected animals, suggesting the possibility that IC formed in the airways is involved in the early stage of HP.