Rapid dendritic cell recruitment to the bronchial mucosa of patients with atopic asthma in response to local allergen challenge

Background-Airway dendritic cells (DQ play an important role in chronic all ergic airway inflammation in experimental animals, but a similar role for D C in human allergic asthma has been difficult to define. This pilot study w as undertaken to elucidate the role of DC in allergic asthma by examining t heir potential to migrate to the lower airways in response to bronchial cha llenge with specific allergen. Methods-Bronchial biopsy specimens were obtained from seven patients with a llergic asthma before and 4-5 hours after allergen challenge. Multicolour i mmunofluorescence staining was performed on mucosal cryosections to identif y changes in the number and phenotypes of DC. Results-A dramatic increase in the number of CD1c+HLA-DR+ DC were observed in the lamina propria after challenge compared with baseline (22.4 v 7.8 ce lls/mm(2)). The rapid accumulation (within 4-5 hours) of these cells strong ly suggests that they were directly recruited from peripheral blood. Conclusion-We have shown for the first time that a specific DC subset rapid ly emigrates into the human bronchial mucosa during allergic inflammation. While this study is based on relatively few patients, the consistency of th e overall results strongly suggests that the rapid population dynamics of h uman airway DC closely parallel those in animal models of acute inflammatio n. These findings support suggestions that DC have an important role in hum an airway allergy.