Acetylcholine and substance P stimulate bronchial epithelial cells to release eosinophil chemotactic activity

We investigated a role of neuroregulation in the release of eosinophil chemotactic activity (ECA) from bovine bronchial epithelial cells (BBEC). BBEC were stimulated with acetylcholine (ACh) and substance P (SP), and the supernatant fluids were tested for ECA by a blind-well chemotactic chamber technique. BBEC released ECA in response to ACh and SP in a dose- and time-dependent manner. Checkerboard analysis showed that ECA in regard to ACh and SP was chemotactic rather than chemokinetic. Partial characterization revealed that ECA involved both lipids and peptides. The release of ECA in response to ACh and SP was inhibited by nonspecific and 5-specific lipoxygenase inhibitors and by cycloheximide (P < 0.01). Molecular-sieve column chromatography revealed that these mediators induced three molecular mass peaks (near 25 kDa, 9 kDa, and 400 Da, respectively). The lowest peak, which represented the predominant activity, was blocked by leukotriene B4-receptor antagonist (P < 0. 01) but not by platelet-activating factor-receptor antagonist. The release of leukotriene B4 in the supernatant fluids was increased in response to ACh and SP stimulation (P < 0.01). Platelet-activating factor was not detected. These results raise the possibility of a role of neuroregulation for the elaboration of ECA in the airway.