Characterization of bronchoalveolar lavage cells and macrophage-derived chemoattractant activity in pancreatic elastase-induced emphysema in hamsters.

Bronchoalveolar lavage (BAL) was performed 30 days after endotracheal saline (C) or pancreatic elastase (E) administration to hamsters. E animals had twice as many cells as C animals (7.04 +/- 0.07 vs. 6.69 +/- 0.05 log10 cells, p less than 0.0001, paired t-test) and greater numbers of polymorphonuclear neutrophils (PMN) (6.61 +/- 0.05 vs. 5.27 +/- 0.04 log10 cells/animal, p less than 0.0001, t-test). On flow cytometric analysis and cell sorting, BAL cells from C animals showed a homogeneous population of cells with high light scatter and laser-excited intrinsic autofluorescence that were predominantly (greater than 99%) pulmonary alveolar macrophages (PAM). BAL cells from E animals had 80% PAM with characteristics similar to those of C animals; the remaining 20% of cells were smaller with lower forward and 90 degrees light scatter and four- to fivefold lower autofluorescence. These were found to be predominantly PMN on cytological examination of a sorted fraction. Fc receptors were expressed by greater than 95% of BAL cells from both C and E animals. To explain the altered cell population in E animals, PAM from both E and C animals were cultured in vitro, and the supernatants were assayed for neutrophil chemoattractant activity (NCA). In vitro PAM from E animals produced greater NCA than control PAM after 48 h in culture when stimulated with aggregated immunoglobulin or serum activates zymosan (p less than or equal to 0.003, ANOVA). Analyses of BAL supernatants 24 h after elastase administration indicated the presence of a heat-stable chemoattractant for PMN; such chemotactic activity, however, was not detectable 1 week or 4 weeks after the administration of elastase.