Segmental bronchoprovocation in allergic rhinitis patients affects mast cell and basophil numbers in nasal and bronchial mucosa

Mast cells and basophils are cells that play an important role in the initiation and control of allergic inflammation in asthma and rhinitis. This study was undertaken to determine the presence and dynamics of mast cells and basophils in the nasal and bronchial mucosa of allergic rhinitis patients after segmental bronchial provocation (SBP). Eight nonasthmatic, grass pollen-allergic rhinitis patients and eight healthy controls were included. Bronchial and nasal biopsies, as well as blood samples, were taken before (T-0) and 24 h (T-24) after SBP. Immunohistochemical staining was performed for mast cells (tryptase and chymase; phenotypes MCT, MCTC, MCC) and basophils (BB1). In the bronchial mucosa, the number of BB1(+) cells increased significantly (p < 0.05) in allergic rhinitis patients after SBP. In the nasal mucosa, the numbers of MCC and MCTC cells decreased significantly, whereas the numbers of [BB1(+)] cells increased significantly in allergic rhinitis patients after SBP (p < 0.05). In blood, the number of basophils decreased (p < 0.05) and the level of interleukin (IL)-5 increased (p < 0.05) in atopic patients after SBP. No significant changes could be observed in healthy controls. This study shows that SBP in nonasthmatic allergic rhinitis patients reduces numbers of mast cells in the nose as a result of enhanced degranulation. At the same time, there is evidence for an influx of basophils from the blood into the nasal and bronchial mucosae.