Effects of a long-standing challenge on pulmonary neuroendocrine cells of actively sensitized guinea pigs.

Histologic studies using the silver stain method have implicated pulmonary neuroendocrine cells (NEC) in asthma by demonstrating an increase in their number in the bronchi of guinea pigs actively sensitized with ovalbumin and 10 min after challenge. We verified the same data and completed them by a study of the long-standing effects of a challenge on NEC number in guinea pig bronchi. Actively sensitized animals were killed 2, 6, 24, 48, 72, and 144 h after being challenged by an aerosolized solution of ovalbumin. This study was completed by the evaluation of eosinophilic infiltration of bronchi to test the recently proposed hypothesis of the possible eosinophil recruitment by NEC product. Our results confirmed the increase in NEC number in the bronchial wall after sensitization. Originally we demonstrated that, 24 h after challenge, the NEC number decreased significantly, compared to sensitized only animals, suggesting possible product release. Eosinophilic migration was observed in sensitized animals and, more importantly, in all sensitized plus challenged animals. We suggest that bronchial NEC may play a role in immunoallergic events that take place in the lung after challenge, probably by releasing mediators that may influence, among other effects, eosinophilic recruitment.