Identification of an oolemmal IgG Fc receptor: its role in promoting binding of antibody-labelled human sperm to zona-free hamster eggs.
Antisperm antibodies (ASAs) present in sera of infertile men and women have been shown either to promote or inhibit penetration of zona-free hamster eggs by antibody-labelled human spermatozoa. Increased numbers of oolemmal-bound sperm have been noted in association with increased sperm penetration frequencies, following antibody labelling, when compared with antibody-free sperm. The promotion of adherence of ASA-labelled sperm to the oolemma could be mediated through the binding of antibodies to common epitopes present on the sperm and egg surfaces or through Fc-mediated binding to an oolemmal Fc receptor. In support of the latter hypothesis, we report that zona-free hamster eggs bind aggregated human IgG and IgG Fc fragments. The presence of an oolemmal IgG Fc receptor has been confirmed using a rat monoclonal antibody (2.4G2) directed against a murine IgG Fc receptor (Fc gamma RII) as judged both by indirect immunofluorescence and by immunobead binding. In addition, the pre-incubation of zona-free hamster eggs with IgG Fc diminished both adhesion to and penetration of the oolemma by human spermatozoa.
Bronson
R A
RA
Department of Obstetrics and Gynecology, Health Sciences Center, SUNY, Stony Brook 11794-8091.
Fleit
H B
HB
Fusi
F
F
D000818:Animals; D000943:Antigens, Differentiation / Q000032:analysis / Q000502:physiology*; D006224:Cricetinae; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D008647:Mesocricetus; D011961:Receptors, Fc / Q000032:analysis / Q000502:physiology*; D017452:Receptors, IgG; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000276:immunology*
D000943:Antigens, Differentiation; D007074:Immunoglobulin G; D011961:Receptors, Fc; D017452:Receptors, IgG