Increased concentrations of secretory leukocyte protease inhibitor in peritoneal fluid of women with endometriosis

Secretory leukocyte protease inhibitor (SLPI) is a potent inhibitor of huma n leukocyte elastase. We investigated whether SLPI was present in the perit oneal fluid of women with endometriosis and to clarify the role of SLPI in the pathogenesis of endometriosis. Western blot analyses revealed that SLPI protein was detected as a 12 kDa band in peritoneal fluid. The peritoneal fluid concentrations of SLPI, elastase and interleukin-6 were assayed by en zyme-linked immunosorbent assays (ELISA). SLPI concentrations and the SLPI/ elastase ratio in the peritoneal fluid of women with endometriosis were hig her than in samples from women without endometriosis. There was no signific ant correlation between concentrations of SLPI and interleukin-6 in the per itoneal fluid. Immunohistochemistry using an anti-SLPI polyclonal antibody revealed positive staining in peritoneal macrophages, but not lymphocytes. The present findings suggest that SLPI found in the peritoneal fluid of pat ients with endometriosis may contribute to the pathogenesis of endometriosi s.