Topical antigen provocation increases the number of immunoreactive IL-4-, IL-5- and IL-6-positive cells in the nasal mucosa of patients with perennial allergic rhinitis.

To evaluate the role of Th2-type cytokines in the nasal mucosa which has been repeatedly exposed to antigen, an immunohistological study for IL-4, IL-5 and IL-6 was performed in patients with perennial allergic rhinitis and non allergic rhinosinusitis. The numbers of immunoreactive (ir)-IL-4, ir-IL-5 and ir-IL-6-positive cells were significantly higher in allergic mucosa than in nonallergic mucosa. In allergic mucosa, the numbers of these ir-cytokine-positive cells were significantly higher in the antigen-challenged site than in the control site. When the patients were divided into an early group (4-6 h after challenge) and a later group (15-25 h after challenge), only the change of ir-IL-4-positive cells was remarkable in the former group, whereas those of the ir-IL-4, ir-IL-5 and ir-IL-6-positive cells were significant in the latter group. These results suggest that antigen-induced upregulation of IL-4, IL-5 and IL-6 is important in the pathogenesis of perennial allergic rhinitis.