INFLUENCE OF PROLONGED TREATMENT WITH TOPICAL CORTICOSTEROID (FLUTICASONE PROPIONATE) ON EARLY AND LATE-PHASE NASAL RESPONSES AND CELLULAR INFILTRATION IN THE NASAL-MUCOSA AFTER ALLERGEN CHALLENGE

We have examined the effect of prolonged treatment with topical cortic osteroid on allergen-induced early and late nasal responses and the as sociated inflammatory cell infiltrate in grass pollen sensitive allerg ic rhinitics. Following a randomized double-blind 6 week treatment per iod with fluticasone propionate 200 mu g aqueous nasal spray twice dai ly or matched placebo spray, nasal provocation was performed using Tim othy grass pollen extract. Nasal symptoms were recorded at intervals f rom 0 to 24 h. Nasal biopsies were performed before treatment and at 2 4 h after allergen and processed for immunohistology. When corticoster oid-treated patients were compared with the placebo group there was an approximately 50% decrease in the size of the early (0-60 min) respon se and almost complete inhibition of late (1-24 h) nasal symptoms afte r allergen challenge. After allergen challenge markedly fewer T lympho cytes and CD25+ (interleukin-2 receptor bearing) cells were observed i n both the epithelium and submucosa in fluticasone treated patients co mpared with the placebo group. Significantly less total and activated eosinophils were observed, particularly within the nasal epithelium. S ubmucosal mast cell counts were decreased, whereas increased numbers o f submucosal neutrophils were observed. These results confirm that top ical corticosteroid treatment inhibits allergen-induced early and late nasal responses. This may possibly occur following a decrease in T ly mphocytes and/or mast cells and their products and a consequent reduct ion in tissue eosinophiIia.