Inflammatory cell populations in the airways and parenchyma after antigen challenge in the rat

We examined the effects of sensitization and antigen challenge on the cellular populations retrieved from the large airways (LA) (generations zero to 5 approximately) and small airways and parenchyma (S/P) of the rat. Male Brown-Norway rats, 7 to 8 wk of age, were either actively sensitized to ovalbumin (n = 24) or sham-sensitized to saline (n = 9), and, 14 days later, they were anesthetized with urethane, intubated endotracheally, and challenged. Aerosols of ovalbumin (5% wt/vol in saline for 5 min) or saline were administered to 12 and six rats, respectively, and measurements of pulmonary resistance (RL) were made for 8 h. The early airway response (ER) was calculated as the highest value of RL in the first hour after challenge, and the late response (LR) was calculated as an increase in RL to greater than 200% of the baseline value in the 4- to 8-h period after challenge. Rats were killed by exsanguination, LA were separated from S/P, and cells were isolated after tissue mincing and digestion with collagenase. Total and differential cell counts and lymphocyte subsets were determined. Antigen challenge significantly increased the cellular yield (mostly neutrophils) from the LA and S/P. Animals with a LR had a lower total cellular yield from the LA and S/P than did animals without a LR. The animals with a LR also had a lower yield of eosinophils and lymphocytes from the S/P than did animals challenged with saline alone. Cellular yields were not lower in the animals with an isolated ER after antigen challenge.(ABSTRACT TRUNCATED AT 250 WORDS)