[Neutrophil chemotactic factor in lung injury produced by immune complexes]

Our previous study demonstrated increased levels of C5a des Arg and increased numbers of neutrophils in bronchoalveolar lavage (BAL) fluids of patients acutely ill with hypersensitivity pneumonitis (HP), suggesting that complement fragments activated by immune complexes (IC) play a role in the early stage of disease. The present study was undertaken to clarify the mechanisms involved in lung injury produced by IC formed in the airway. Sequential changes of neutrophils and neutrophil chemotactic activities (NCF) in BAL fluids were evaluated in guinea-pigs injected intratracheally with preformed IC. Our results were as follows: 1) There was an increased number of neutrophils in BAL cells within 48 hours of the intratracheal injection with preformed IC reaching a peak at 24 hours postinjection. 2) NCF in BAL fluids were potent at 2-6 hours postinjection and preceded an increase of neutrophils in BAL cells, indicating that NCF play a role in the accumulation of neutrophils in the lung. 3) A consequent increase of alveolar macrophages and macrophage chemotactic activities (MCF) in BAL fluids was observed but to a lesser extent. 4) Pretreatment with cobra venom factor of guinea-pigs reduced the increase of BAL cells, especially neutrophils and NCF to approximately 60% of comparable results, suggesting that complement fragments play a role in IC mediated lung injury.