title: Seminal thrombin-activatable fibrinolysis inhibitor: a regulator of liquefaction.
abstract: Several active components of the haemostatic system have been identified in human semen. Here we investigated the presence of thrombin-activatable fibrinolysis inhibitor (TAFI) in seminal plasma. Using an enzyme-linked immunosorbent assay, TAFI levels were measured in 36 semen specimens obtained from subfertile, normally fertile, fertile sperm donor and vasectomized individuals. TAFI was detectable in human semen. Its levels were highest in vasectomized individuals compared with the other groups, including a pooled normal semen parameter stratification group (by World Health Organization criteria). This elevation in the vasectomy group was found to be statistically significant in comparison with the normally fertile (P < 0.01) and the pooled normal semen parameter groups (P < 0.05). Seminal TAFI levels showed a significant positive correlation with total sperm count and sperm density. In contrast, a negative association was observed with semen volume, days of sexual abstinence and liquefaction time. The highly motile sperm group showed low TAFI levels. Our results establish the presence of TAFI in seminal plasma with a probable role in the protection of the seminal clot against lysis. It also suggests a downstream (post-testicular) source for its production. This reinforces the involvement of the conventional haemostatic system in the coagulation and liquefaction properties of human semen.
authors.affiliation: Department of Urology, Southampton University Hospitals NHS Trust, University of Southampton, Southampton, UK. bashir@soton.ac.uk
authors.forename: Bashir A
authors.initials: BA
authors.lastname: Lwaleed
authors.forename: Anuj
authors.initials: A
authors.lastname: Goyal
authors.forename: Robert S
authors.initials: RS
authors.lastname: Greenfield
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Cooper
mesh_terms: D025901:Carboxypeptidase B2 / Q000378:metabolism*; D005298:Fertility / Q000502:physiology*; D006801:Humans; D008297:Male; D010447:Peptide Hydrolases / Q000378:metabolism*; D012661:Semen / Q000201:enzymology*; D013076:Sperm Count; D013081:Sperm Motility / Q000502:physiology
chemical_list: C011545:semen liquefaction factor; D010447:Peptide Hydrolases; D025901:Carboxypeptidase B2