The fertilization antigen-1 does not have proteolytic/acrosin activity, but its monoclonal antibody inhibits sperm capacitation and acrosome reaction.
OBJECTIVE
To determine if human sperm surface fertilization antigen exhibits proteolytic or acrosin activity and to investigate the mechanism(s) whereby monoclonal antibody (mAb) to fertilization antigen inhibits human sperm penetration of zona-free hamster ova.


METHODS
Proteolytic and acrosin activities of human fertilization antigen were determined. Acrosomal status, acrosin activity, and motion characteristics were evaluated after incubation of human sperm with immunoaffinity-purified mAb to fertilization antigen.


METHODS
Academic research environment.


METHODS
Fertile donors used as controls for infertile patients for fertility evaluation.


METHODS
Human spermatozoa were treated with mAb to fertilization antigen and induced to undergo acrosome reaction using calcium ionophore A23187.


METHODS
Proteolytic and acrosin activities of fertilization antigen. Sperm penetration assay, acrosomal status, and motion parameters.


RESULTS
Fertilization antigen does not exhibit proteolytic or acrosin activity; however, its mAb completely blocks human sperm penetration of zona-free hamster ova. The mAb to fertilization antigen inhibits ionophore-induced acrosome reaction and blocks development of the hyperactivated state of human sperm cells.


CONCLUSIONS
Monoclonal antibody to fertilization antigen blocks fertilization by inhibiting capacitation and acrosome reaction.
Kaplan
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Department of Obstetrics, Gynecology, and Reproductive Science, Mount Sinai Medical Center, New York, New York 10029.
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D000176:Acrosin / Q000378:metabolism*; D000177:Acrosome / Q000502:physiology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology*; D000941:Antigens / Q000276:immunology / Q000502:physiology*; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D013075:Sperm Capacitation; D013081:Sperm Motility; D013084:Sperm-Ovum Interactions
D000911:Antibodies, Monoclonal; D000941:Antigens; C054151:fertilization antigen; D010450:Endopeptidases; D000176:Acrosin