Concentration of granulocyte elastase in seminal plasma is not associated with sperm motility

Although elastase could affect sperm motility in vitro, secretory leukocytes protease inhibitor (SLPI) prevents sperm from being attacked by elastase. The authors investigated the correlations of elastase level with sperm motility and SLPI level in vivo. Semen samples (n = 116) were collected and centrifuged after semen analysis. Elastase and SLPI levels were determined by an enzyme immunosorbent assay. Samples were classified by elastase levels into low (<250 ng/mL), moderate (250-1,000 ng/mL), and high elastase groups (<greater than or equal to>1,000 ng/mL). Elastase levels (range, 2.8-23,974.4 ng/mL) were not associated with sperm motility. The median SLPI level in the high elastase group was 15,900 ng/mL (range, 2,860-46,900 ng/mL). However, there was no significant correlation between elastase and SLPI levels in seminal plasma. Since SLPI forms a 1:1 complex with elastase, these results suggest that seminal plasma has a sufficient amount of SLPI to protect spermatozoa from elastase.