Expression of prostaglandin D2 synthase in activated eosinophils in nasal polyps.

OBJECTIVE To clarify the relationship between prostaglandin D2 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 D2 synthase (HPGDS) expression was examined by semiquantitative Western blot analysis and by immunohistochemical 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 D2 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 D2 was actively produced by an EG2 and HPGDS double-positive subpopulation of activated eosinophils that had infiltrated into nasal polyps.