Bleomycin stimulates lung fibroblasts to release neutrophil and monocyte chemotactic activity

We determined whether human lung fibroblasts might release chemotactic acti vity for neutrophils (NCA) and monocytes (MCA) in response to bleomycin, Th e human lung fibroblasts supernatant fluids were evaluated for chemotactic activity by a blind well chamber technique. Human lung fibroblasts released NCA and MCA in a dose- and time-dependent manner in response to bleomycin, Checkerboard analysis of supernatant fluids revealed that both NCA and MCA were chemotactic, Partial characterization revealed that NCA was partly he at labile, trypsin sensitive, and predominantly ethyl acetate extractable. In contrast, MCA was partly trypsin sensitive and ethyl acetate extractable . The release of chemotactic activity was inhibited by lipoxygenase inhibit ors and cycloheximide. Molecular sieve column chromatography revealed that both NCA and MCA had multiple chemotactic peaks. NCA was inhibited by leuko triene B-4 receptor antagonist and anti-IL-8 and G-CSF Abs, MCA was attenua ted by leukotriene B-4 receptor antagonist, and monocyte chemoattractant pr otein-1, GM-CSF, and TGF-beta Abs, Leukotriene B-4 receptor antagonist and these Abs inhibited the corresponding m.w. chemotactic activity separated b y column chromatography. The concentrations of IL-8, G-CSF, monocyte chemoa ttractant protein-1, GM-CSF, and TGF-beta in the supernatant fluids signifi cantly increased in response to bleomycin, These data suggest that lung fib roblasts may modulate inflammatory cell recruitment into the lung by releas ing NCA and MCA in response to bleomycin.