Identification of auto-antigens of the human sperm membrane

Glycoproteins of human sperm membranes were labelled by a galactose oxidase-tritiated-sodium borohydride technique and detergent solubilized. A glycoprotein-enriched-fraction was obtained by lectin affinity chromatography. Subsequently, antigens in this fraction were isolated from the glycoprotein mixture by indirect immunoprecipitation and analysed in SDS-polyacrylamide gel electrophoresis. With some human sera with sperm agglutinating and immobilizing auto-antibodies at least three polypeptide chains were isolated, one with a molecular weight of about 41,000 and two with molecular weights of about 77,000. Other sera with equally strong agglutination and immobilization did not reveal any peaks in SDS-gel electrophoresis. Absorption studies using sequential indirect immunoprecipitation showed that the former group of sera independently of their mode of agglutination reacted with the same antigen(s).