Seminal tissue factor revisited

Abstract

Studies of seminal tissue factor (TF) are few and mostly based on small numbers. Due to the reported lack of factor (F) X in semen, it has been suggested that TF may not have a role in seminal coagulum formation. However, recent identification of a number of haemostatic factors in semen justifies a re-evaluation of its occurrence. Semen specimens were collected from sub-fertile (n = 19), normally fertile (n = 33), semen donors (n = 30) and vasectomized subjects (n = 62), some fractionated into sperm, a prostasome-rich fraction and seminal plasma. Functional and antigenic TF levels were measured and related to conventional fertility parameters. Semen contains high concentration of functional and antigenic TF. Most TF was found in seminal plasma prepared by low-speed centrifugation. When further fractionated by ultracentrifugation much of this may reside in the pellet (prostasomal fraction). It was also detectable on sperm. TF antigen levels were higher in vasectomized subjects than sub-fertile, normally fertile, donor (p = 0.02) and a 'pooled normal semen parameters' (PNSP) stratification (derived from a combination of measurements) (p = 0.06). The sub-fertile group showed a wider variation than normal, donor or the PNSP subjects. Seminal TF antigen levels correlated significantly with sperm agglutination (p = 0.03) and abnormal sperm morphology (p = 0.04). Subjects with anti-sperm antibodies also showed high TF antigen levels. In conclusion, semen contains functional and antigenic TF at high concentrations. A full complement of clotting factors probably exists in semen, so some pro-coagulant role for TF should not be excluded. Decreased seminal TF levels appear to be associated with seminal parameters that are known to favour male fertility.

Seminal thrombin-activatable fibrinolysis inhibitor: a regulator of liquefaction

“…In so doing, prostasomes transfer important proteins, lipids and ions to spermatozoa [43,44]. Some of these molecules have been identified as proteins of the coagulative pathwayincluding tissue factor, to name one such example [21,45]. This possibly explains the high TAFI levels in the vasectomized group as prostasome production is not affected by this procedure.…”

“…Several coagulation and fibrinolytic factors found in blood have been shown to exist in human semen [16][17][18][19][20][21][22][23][24][25][26]. It is envisaged that these factors are involved in the regulation of coagulum formation and the subsequent lysis of ejaculated semen [26].…”

“…There is now a substantial body of evidence pertaining to the existence of a number of important haemostatic factors in human semen [19][20][21][22][23][24][25]. These independent studies have identified factors that potentially play a significant role in seminal coagulation and liquefaction.…”

Seminal factor VII and factor VIIa: supporting evidence for the presence of an active tissue factor‐dependent coagulation pathway in human semen

“…Semen has already been shown to contain very high concentrations of functional TF (Fernández et al. , 1997; Carson & De Jonge, 1998; Lwaleed et al. , 2006).…”

“…, 1997; Park et al. , 1997; Carson & De Jonge, 1998; Lwaleed et al. , 2005a,b,c, 2006) and the seminal coagulum itself is composed of fibrin‐like material (Polak & Daunter, 1989).…”