Cellular infiltration and cytokine mRNA expression in perennial allergic rhinitis

Background: Allergen challenge in allergic rhinitis patients leads to local eosinophilia and Th2-type cytokine expression. Natural exposure to grass p ollen is additionally characterized by epithelial mast-cell infiltration. W e hypothesized that perennial allergic rhinitis is also associated with T-c ell and eosinophil infiltration of the nasal mucosa, local Th2-type cytokin e expression, and increased numbers of nasal epithelial mast cells. Methods : Nasal biopsies from perennial allergic rhinitis patients and controls wer e analysed by immunocytochemistry for different cell populations and in sit u hybridization for cytokine mRNA-expressing cells. Results: Perennial allergic rhinitis was associated with increased numbers of submucosal CD3+ T cells (P = 0.05), EG2+ activated eosinophils (P = 0.01 ), and CD68+ macrophages (P = 0.01) compared to controls. Epithelial, but n ot submucosal, tryptase-positive mast cells were also elevated in rhinitics compared to controls (P = 0.01). The numbers of cells expressing interleuk in (IL)-5 were higher (P = 0.01) and the numbers of cells expressing IL-2 w ere lower (P = 0.04) in rhinitic patients than controls. There were no sign ificant differences for either IL-4 or interferon-gamma between the groups. Conclusions: Perennial allergic rhinitis is characterized by mast-cell migr ation into the epithelium; submucosal infiltration by T cells, eosinophils, and macrophages; and an imbalance in local T-cell cytokine production in f avour of enhanced IL-5 and reduced IL-2 expression.