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<0.025) in total cells recovered, an increase (p<0.001) in neutrophils, and an increase (p<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<0.05) amounts of neutrophils 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<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.