Neutrophil chemotactic activity generation by alveolar macrophages after bleomycin injury

Saline lavage was performed on rat lungs after the intratracheal injection of saline or bleomycin. An increase (p less than 0.025) in total cells recovered, an increase (p less than 0.001) in neutrophils, and an increase (p less than 0.001) in albumin concentration were noted in lavage fluid recovered from rats subsequent to bleomycin injury. At 5, 10, 15, and 20 days after injury, macrophages recovered from bleomycin-treated rats generated increased (p less than 0.05) amounts of neutrophil chemotactic activity in vitro compared with macrophages recovered from saline-treated rats. The chemotactic activity was attributable to a factor or factors of low molecular weight and hydrophobic in nature, characteristics similar to previously described alveolar macrophage-derived neutrophil chemotactic factors. The generation of neutrophil chemotactic activity was suppressed (p less than 0.025) by hydrocortisone and 5,8,11,14-eicosatetraynoic acid (ETYA), suggesting that the neutrophil chemotactic activity generation is dependent upon the lipoxygenase pathway of arachidonic acid metabolism.