Mechanisms of IL-6, IL-8, and GM-CSF release in nasal secretions of allergic patients after nasal challenge.

Cytokines are potentially active biological peptides that are known to play an important role in several immune responses. Several studies have reported the existence of a variety of cytokines in the nasal mucosa of patients with allergic rhinitis. However, there are few reports on cytokines released into the nasal secretion. In the present study, we investigated the sources, and levels of three key proinflammatory cytokines namely, IL-6, IL-8, and GM-CSF in the nasal secretion, as well the mechanisms of their release, by ELISA and immunohistochemistry. Firstly, we examined the levels of IL-6, IL-8, and GM-CSF in the nasal secretion after in vivo nasal challenge with methacholine (MC), histamine (HI) and allergen (Ag) in patients with nasal allergy to house dust mite (HDMAR). Next, we examined the levels of IL-6, IL-8, and GM-CSF released, in vitro, after Ag challenge of nasal scrapings from patients with HDMAR. Finally, we examined the sources of these cytokines in the nasal mucosa, by immunohistochemistry. After MC challenge in patients with HDMAR, the concentration of IL-6, but not IL-8, and GM-CSF, was significantly greater on the challenged side than on the contralateral side. Ag and HI provocation induced significantly greater levels of IL-6 and IL-8 secretion in patients with HDMAR, on the challenged side than on the contralateral side. GM-CSF was only detected in the nasal secretion after Ag challenge. Immunoreactivity for IL-6 and IL-8 was very similar in that it was predominantly localised to the apical portion of epithelial cells, the superficial lamina propria, gland cells, and migrating cells. The immunoreactivity for GM-CSF varied slightly from that of IL-6 and IL-8: strong immunoreactivity was detected in the basal part of epithelial cells, basement membrane, glandular ducts, and migrating cells. These results suggest that the levels, sources, and mechanisms of release of IL-6, IL-8, and GM-CSF in the nasal secretion of patients with HDMAR do vary, but are important in the manifestation of the allergic reaction.