Effects of Rhinovirus-induced Common Colds on Granulocyte Activity in Allergic Rhinitis

Objective: To explore the activities of mast cells, eosinophils, and neutrophils in patients with allergic rhinitis developing common colds and increased responsiveness to allergen following nasal rhinovirus inoculation.

Methods: We have revisited a nasal lavage material obtained from 17 patients who were successfully inoculated with rhinovirus outside the pollen season and received nasal allergen challenges before and after inoculation. We have examined indices of mast cell activity (tryptase), eosinophil degranulation (eosinophil peroxidase; EPO), and neutrophil activation (myeloperoxidase; MPO).

Results: Allergen challenges performed before rhinovirus inoculation increased the nasal output of EPO. Notably, this response was significantly greater after rhinovirus inoculation (cf. before inoculation). The output of MPO was also increased following allergen challenge after, but not before, rhinovirus inoculation. Nasal lavage fluid levels of tryptase were increased following allergen challenge similarly before and after rhinovirus inoculation. Also, the viral infection did not affect the baseline levels of tryptase.

Conclusions: The present data demonstrate that rhinovirus infections activate both eosinophils and neutrophils, but that they may not affect mast cell activity. We suggest that common colds in part through stimulation of granulocyte activity potentiate the airway inflammation in allergic diseases.