[Airway inflammatory cell dynamics during late asthmatic reactions induced by toluene diisocyanate in guinea pigs. I. Bronchoalveolar lavage study].

We developed a guinea pig model of late asthmatic reactions (LAR) induced by toluene diisocyanate (TDI), and investigated airway inflammatory cell dynamics during LAR by bronchoalveolar lavage (BAL) in this model. The guinea pigs were sensitized by nasal application of 10% TDI solution once daily for 7 consecutive days. Thereafter, the animals were challenged with 5% TDI solution, in the same manner, on every 7th day for 4 to 11 times. Each guinea pig was pretreated with metyrapone before challenge. BAL was performed at each time point after the final challenge. The immediate asthmatic reaction and the LAR induced in the challenges were found to be 66% and 55%, respectively. A significant BAL fluid eosinophilia was observed in the guinea pigs during and after LAR (i.e., 3, 6, 24 and 168 hours after challenge), in comparison to the animals without LAR and to the control animals only exposed to ethyl acetate, a solvent for TDI. The number of eosinophils peaked at 6 hours after challenge. However, no significant changes were observed in the numbers of macrophages, lymphocytes or neutrophils in BAL fluid during LAR. We conclude that eosinophils play an important role in LAR in this model. This model seems to be useful in investigating the pathophysiology of TDI-induced asthma.