Anti-sperm antibodies from infertile patients and their cognate sperm antigens: a review. Identity between SAGA-1, the H6-3C4 antigen, and CD52.
OBJECTIVE
The correlation of anti-sperm antibodies (ASA) with some instances of unexplained infertility implicates a role for these antibodies in blocking fertilization. Improved diagnosis and treatment of immunologic infertility, as well as a more complete understanding of the mechanism behind this phenomenon, are dependent on the identification and characterization of relevant sperm antigens.


METHODS
In this article, we review literature on methods employed to identify sperm antigens using anti-sperm polyclonal and monoclonal antibodies from infertile patients and vasectomized men. Particular focus is given to approaches using human and mouse monoclonal antibodies to define the SAGA-1 human sperm antigen.


RESULTS
ASA present in sera and genital tract secretions from infertile patients and vasectomized men have been employed in a variety of methods to identify sperm antigens. In an alternate approach, a monoclonal antibody (mAb), H6-3C4, was immortalized from the lymphocytes of an infertile woman who exhibited sperm-immobilizing titers. Subsequently, the sperm-agglutinating, murine S19 mAb was shown to react with the H6-3C4 cognate antigen. The H6-3C4 S19 cognate antigen, designated Sperm Agglutination Antigen-1 (SAGA-1), was characterized as a polymorphic, highly acidic, GPI-anchored glycoprotein on the surface of human spermatozoa. Purification with the S19 mAb followed by microsequencing demonstrated that the SAGA-1 core peptide is identical to CD52, a glycoprotein on the surface of human lymphocytes. Immunoblot analysis demonstrated that these two glycoproteins differed in carbohydrate composition. Thus, sperm SAGA-1 and lymphocyte CD52 represent glycoforms, glycoproteins with the same core peptide but with different carbohydrate structures.


CONCLUSIONS
Autoimmunity to the SAGA-1 and/or CD52 glycoforms may lead to infertility. Structural and immunologic differences between these glycoproteins may be important factors in the etiology of immunologic infertility and other autoimmune disorders.
Diekman
A B
AB
Center for Recombinant Gamete Contraceptive Vaccinogens, University of Virginia Health System, Charlottesville 22908, USA.
Norton
E J
EJ
Westbrook
V A
VA
Klotz
K L
KL
Naaby-Hansen
S
S
Herr
J C
JC
D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D000951:Antigens, Neoplasm; D000954:Antigens, Surface / Q000276:immunology*; D001323:Autoantibodies / Q000032:analysis*; D000074301:CD52 Antigen; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007247:Infertility, Female / Q000276:immunology*; D007248:Infertility, Male / Q000276:immunology*; D007518:Isoantibodies / Q000032:analysis*; D008297:Male; D013094:Spermatozoa / Q000276:immunology*
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D001323:Autoantibodies; D000074301:CD52 Antigen; C000613862:CD52 protein, human; D006023:Glycoproteins; D007518:Isoantibodies; C120760:SAGA-1 protein, human