Expression of prostaglandin D2 synthase in activated eosinophils in nasal polyps

Objective: To clarify the relationship between prostaglandin D-2 production and eosinophil accumulation. Design: Screening and diagnostic tests. Subjects: Nineteen patients with chronic rhinosinusitis. Interventions: Nasal polyps were obtained from 19 patients at endoscopic sinus surgery. Eosinophils in nasal polyps were counted after hematoxylin-eosin staining and immunostaining with antibodies against 2 eosinophil markers-major basic protein and EG2. Hematopoietic prostaglandin D-2 synthase (HPGDS) expression was examined by semi-quantitative Western blotanalysis and by immnuohistochemical staining with anti-HPGDS antibody. Results: Nasal polyps were divided into 3 groups by the degree of eosinophilic infiltration. Western blot analysis revealed that HPGDS was more intensely and frequently expressed in the group with high infiltration than in the groups with low or medium infiltration. Hematopoietic prostaglandin D-2 synthase was immunohistochemically found in a subpopulation of EG2-positive eosinophils that had accumulated in the nasal polyps but not in the EG2-negative resting eosinophils. The ratio of HPGDS-positive eosinophils to EG2-positive eosinophils in the group with high eosinophil infiltration (mean +/- SD, 64.8% +/- 19.2%) was twice that in the group with low eosinophil infiltration (30.5% +/- 13.8%). Conclusion: Prostaglandin D-2 was actively produced by an EG2 and HPGDS double-positive subpopulation of activated eosinophils that had infiltrated into nasal polyps.