Production of secretory leukocyte protease inhibitor by human amniotic membranes and regulation of its concentration in amniotic fluid

Secretory leukocyte protease inhibitor (SLPI) is a potent inhibitor of huma n leukocyte elastase, SLPI is a protein found in various human fluids, incl uding parotid secretions, cervical mucus, seminal plasma and ascites, Weste rn blot analysis revealed that SLPI protein is detected as a 12 kDa band in both the amniotic fluid and the amniotic membrane. The amniotic fluid conc entrations of SLPI were assayed by enzyme-linked immunosorbent assay. SLPI concentrations in the amniotic fluid of women in the third trimester were h igher than those in the second trimester. Immunohistochemistry using an ant i-SLPI polyclonal antibody revealed positive staining in epithelial cells i n amniotic membranes. Reverse transcription-polymerase chain reaction demon strated that SLPI transcripts could be detected in the amniotic membranes. To determine the mechanism of SLPI production by amniotic cells, purified a mniotic cells were stimulated with various cytokines, Amniotic cells produc ed SLPI in a dose-dependent manner when stimulated with interleukin (IL)-1 alpha, IL-1 beta, and tumour necrosis factor-alpha. The present findings sh ow that SLPI is produced by the amniotic membranes in response to cytokine concentrations. The SLPI in the amniotic fluid may contribute to immunodefe nce mechanisms during pregnancy.