POTENT BLOOD COAGULANT ACTIVITY OF HUMAN SEMEN DUE TO PROSTASOME-BOUND TISSUE FACTOR

Human semen contains very potent blood-clotting activity; for example, seminal serum diluted up to 10 000-fold significantly decreased the r ecalcification clotting time of blood plasma. This seminal coagulant a ctivity was dependent on factor X and calcium ions, suggesting the pre sence of a factor X activator. Immunoblotting analysis and immunoadsor ption studies confirmed the presence of tissue factor antigen (45 kDa) in semen. Centrifugation studies suggested that tissue factor was mem brane associated, and fractionation of seminal serum by gel filtration followed by immunoelectron microscopy revealed that tissue factor ant igen was on the prostasome vesicle surface. Tissue actor originated fr om prostatic fluid and not from seminal vesicle secretions, Tissue fac tor antigen averaged 21 ng/ml in seminal serum. Hypothetical roles for very high levels of tissue factor in semen include several possibilit ies. In the event of abrasion and bleeding during intercourse, rapid b lood clotting at lesion sites would prevent sperm and seminal componen ts, including infectious agents such as human immunodeficiency virus, from entering the blood stream, generating antibodies, or promoting in fectious disease. This could imply that development of infection from semen-borne agents or development of anti-sperm antibodies in some pat ients could result from impairment or absence of seminal tissue factor .