EFFECT OF STABLING ON BRONCHOALVEOLAR CELLS OBTAINED FROM NORMAL AND COPD HORSES

Bronchoalveolar lavages (BAL) were performed before and after 3 weeks of housing in 5 horses suffering from COPD and 5 normal horses. In the two groups, the total number of cells recovered remained unchanged af ter stabling. The most common cell populations in BAL fluid of control animals were alveolar macrophages (46.4%) and lymphocytes (44.9%). Th e percentage of neutrophils increased after stabling from 8.7% to 27.6 %. In COPD horses, lymphocytes predominated (40.7%) in animals at past ure with neutrophils increasing from 29.4% to 71.6% after stabling. Af ter fractionation by Percoll density gradient, alveolar macrophages an d neutrophils from normal and COPD horses had a similar density distri bution. After stabling, these cells from normal horses were increased in the low density layers, while those from COPD horses were predomina ntly in the hyperdense layers. Therefore, BAL cells obtained from COPD animals at pasture and after stabling differ from those of control ho rses in the same environment, not only in their populations but also i n their buoyant densities. These differences could be related to diffe rent states of cellular activation and perhaps be responsible for dise ase activity in the COPD horses.