Airway responsiveness and bronchoalveolar lavage fluid profiling in individual rats: Effects of different ovalbumin exposures

We studied repeatedly the development of bronchial hyperreactivity (BHR) and bronchoalveolar lavage fluid (BALF) in rats undergoing different modes of ovalbumin exposures. Treatment was two intraperitoneal injections of ovalbumin in Groups 1-3, followed by one ovalbumin aerosolization in Groups 2 and 3, while rats in Group 4 received repeated ovalbumin aerosols after one single intraperitoneal injection. BHR was assessed longitudinally on day 0 (before treatment) and on day 14 (Groups 1 and 2) or 20 (Groups 3 and 4) and cellular influx was estimated from BALF. No BHR or change in BALF cellular profile was detected in Groups 1-3. However, the infiltration of inflammatory cells, associated with BHR (PC100 8.9 ± 1.3 μg/kg vs. 4.2 ± 1.1 μg/kg), was observed in Group 4. The BHR was always associated with increased number of eosinophils in the BALF. The substantial interindividual variability confirmed the need for a technique that permits follow-up of lung responsiveness and BALF profile. This approach evidenced strong associations between the severity of BHR and the eosinophilia.