A human sperm coating antigen isolated from sperm cell membrane.

A human sperm cell membrane antigen that is highly specific to sperm and seminal plasma was isolated from plasma membrane fraction of spermatozoa using rabbit antiserum against human seminal plasma. In addition to the high specificity to sperm and seminal plasma, the isolated antigen showed the following characteristics: (1) It is a glycoprotein of approximately 12,000 daltons that has an affinity to lentil lectin; (2) it is distributed in human milk other than in sperm and seminal plasma, but is not found in any other organs and tissues including testis; (3) seminal plasma contains the largest amount of the antigen activity, 60-fold greater than spermatozoa and 900-fold greater than milk, suggesting that this antigen could be a sperm-coating seminal plasma antigen.