Alpha 1 -antitrypsin in genital secretions.

Alpha1-antitrypsin is demonstrable in human cervical mucus and semen. It is a serum glycoprotein 45.000 molecular weight capable of inhibiting 1/4 to 1/2 its weight of trypsin chymotrypsin or elastase. It can be detected by electrophoresis in fibrin-agar to which protease is subsequently added perpendicular to the electric field. Alpha1-antitrypsin can be identified by combining the fibrin electrophoresis with immunodiffusion. These techniques show that alpha1-antitrypsin is the major trypsin inhibitor in cervical mucus and is sometimes present but inactive. The antitrypsin fell to a minimum of 30 mcg per ml at ovulation and rose almost 20 times in the luteal phase in cycles studied. During sequential pill cycles the antitrypsin was lower during estrogen intake higher during estrogen-progestogen and highest after withdrawal bleeding. Alpha1-antitrypsin ranged from 27-180 mcg per ml in semen. The function (if any) of this enzyme in cervical mucus may be to protect the mucus gel from proteolytic enzymes in sperm.