Immunohistology of the Nasal Mucosa Following Allergen-induced Rhinitis: Identification of Activated T Lymphocytes, Eosinophils, and Neutrophils

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Abstract
We have studied the immunohistology of the nasal mucosa in allergen-induced rhinitis. Sixteen grass pollen-sensitive patients were challenged twice by randomly allocated allergen or control solutions applied on filter paper disks to the inferior turbinate. All had immediate nasal responses, but late-phase responses were equivocal and only evident as nostril blockage. When cell counts in the nasal submucosa were compared with control values 24 h after allergen, there were no changes in CD45+ (total leukocytes), CD3+, or CD8+ cells. Significant increases were found in the numbers of CD4+ T-helper cells (p < 0.05) and CD25+ [interleukin-2 receptor (IL-2R+)] cells (p < 0.02). Increases in eosinophils (anti-major basic protein, p < 0.01) and neutrophils (antineutrophil elastase, p < 0.01) were also observed. There were increases in tissue macrophages and HLA-DR-positive immunostaining and a reduction in mast cells (tryptase positive), but none of these changes was statistically significant. No significant changes in epithelial thickness, cross-sectional area, or integrity were observed. There was a significant correlation between CD4+ and CD25+ cells (r = 0.61, p < 0.01) but not between macrophages and CD25+ cells (r = 0.18). The changes in the nasal submucosa were not merely a reflection of alterations in circulating cell populations since it was shown that a significant increase in the lymphocyte CD4/CD8 ratio (p < 0.05) was observed in nasal biopsies but not in peripheral blood after allergen challenge. These results indicate that allergic rhinitis is associated with local accumulation of activated T-helper cells as well as eosinophils and neutrophils in the target organ after allergen provocation.