Expression of IL-4, Cepsilon RNA, and Iepsilon RNA in the nasal mucosa of patients with seasonal rhinitis: effect of topical corticosteroids.

BACKGROUND

Nasal allergen provocation has demonstrated that allergen-induced rhinitis is associated with an increase in local IL-4 mRNA and IgE heavy chain (Cepsilon) and IgE heavy chain promoter (Iepsilon) RNA and that pretreatment with topical glucocorticosteroids inhibits the increase in these transcripts.

OBJECTIVE

This study was undertaken to determine whether observations made after acute allergen provocation can be extended to the case of chronic exposure experienced during the pollen season.

METHODS

Biopsy specimens were obtained from the inferior turbinate of 33 pollen-sensitive subjects with allergic rhinitis before and during pollen season. Patients were randomized in a double-blind fashion and treated with either topical steroids (200 microg fluticasone propionate twice daily; n = 16) or matched placebo nasal spray (n = 17) before the pollen season. Alkaline phosphatase anti-alkaline phosphatase immunocytochemistry was used to identify B cells (CD20+), and in situ hybridization was used to detect IL-4, Cepsilon, and Iepsilon RNA+ cells.

RESULTS

Baseline examination revealed IL-4 and Cepsilon RNA but virtually no Iepsilon RNA+ cells in the nasal mucosa. Analysis revealed a significant difference in the expression of Cepsilon and Iepsilon RNA+ cells (p < 0.001). Biopsy specimens taken after antigen exposure exhibited highly significant increases in placebo-treated (p < 0.001) but not steroid-treated patients. In both groups, the number of CD20+ cells was unchanged when preexposure and postexposure biopsy specimens were compared.

CONCLUSIONS

These results show strong support for the hypothesis that IgE class switching occurs locally within the nasal mucosa of subjects with seasonal allergic rhinitis and that this response can be inhibited through strategies directed against local IgE production.