PULMONARY DENDRITIC CELL DISTRIBUTION AND PREVALENCE IN GUINEA-PIG AIRWAYS - EFFECT OF OVALBUMIN SENSITIZATION AND CHALLENGE

We characterized the localization and prevalence of dendritic cells (D C) in guinea pig airways before and after s.c. sensitization and aeros ol challenge with ovalbumin (OVA). DC, eosinophils, macrophages, T cel ls and B cells in lung and trachea were identified and quantified in f rozen sections using monoclonal antibodies and computer-assisted image analysis. Airway reactivity of conscious animals to inhaled methachol ine was examined. In unsensitized animals, DC were localized primarily within the lamina propria of the trachea and bronchi, in the submucos a of the trachea and in the adventitia of the bronchi. in contrast to reported studies on rats, few DC were noted in the epithelium. After O VA challenge, sensitized animals demonstrated an early obstructive res ponse and a late-phase response that was well developed by 18 hr. Chal lenge with OVA increased DC prevalence in the lamina propria and submu cosa of the trachea and in the lamina propria and adventitia of the br onchi. There was widespread eosinophilia throughout the airways, but n o changes in B cells or T cells were evident. Macrophages were increas ed in the epithelium of both OVA-treated and saline-treated animals. A t 18 hr after challenge, sensitized guinea pigs but not saline-treated controls were hyperreactive to inhaled methacholine. Except for macro phages, none of these effects were observed after saline treatment. Ou r findings indicate that inflammation in the airways of OVA-sensitized guinea pigs involves infiltration of DC, which is seen at the time an imals are hyperreactive to inhaled methacholine.