Identification of the human sperm protein that interacts with sperm-immobilizing antibodies in the sera of infertile women.
OBJECTIVE
To identify the target antigen of sperm-immobilizing antibodies present in the circulation of infertile women.


METHODS
Laboratory research.


METHODS
Academic research laboratory.


METHODS
Twenty-nine infertile women with sperm-immobilizing antibodies, 22 infertile women with other disorders, and 20 fertile women.


METHODS
Titers of antibodies to the sperm protein, rSMP-B, were determined by ELISA using as substrate the synthetic peptide segment (rSMP-230) that corresponds with the hydrophilic domain of rSMP-B. Tests for sperm immobilization and zona pellucida penetration were performed using the human IVF system.


METHODS
Human sera with sperm-immobilizing activity were assayed for the presence of antibodies to rSMP-230. Polyclonal antibodies to rSMP-230 were assessed for the same biologic activities as sperm-immobilizing antibodies.


RESULTS
Antibodies to rSMP-230 were detected in 10 (34%) of 29 sera obtained from women with immunologic infertility. In contrast, only one serum sample (2%) from women without sperm-immobilizing activity had a low titer of antibodies to rSMP-230. Polyclonal antibodies to rSMP-230 completely immobilized human sperm in the presence of complement and blocked sperm penetration across the zona pellucida.


CONCLUSIONS
The human sperm protein, rSMP-B, probably is the target antigen of sperm-immobilizing antibodies.
Kamada
M
M
Department of Obstetrics and Gynecology, University of Tokushima, School of Medicine, Japan. kamada@clin.med.tokushima-u.ac.jp
Yamamoto
S
S
Takikawa
M
M
Kunimi
K
K
Maegawa
M
M
Futaki
S
S
Ohmoto
Y
Y
Aono
T
T
Koide
S S
SS
D000328:Adult; D000906:Antibodies / Q000032:analysis / Q000276:immunology* / Q000494:pharmacology / Q000502:physiology*; D000954:Antigens, Surface; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000097:blood* / Q000276:immunology; D008297:Male; D008565:Membrane Proteins / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D013081:Sperm Motility / Q000502:physiology*; D013084:Sperm-Ovum Interactions / Q000187:drug effects
D000906:Antibodies; D000954:Antigens, Surface; D008565:Membrane Proteins; D010446:Peptide Fragments; C088508:rSMP B (1-28); C049242:rSMP-B protein, human