Receptor Mediated Agglutination of Human Spermatozoa by Spermagglutinating Factor Isolated From Staphylococcus aureus

Abstract

We examined spermagglutinating factor isolated from Staphylococcus aureus for evidence of receptor mediated agglutination of human spermatozoa. Binding to spermatozoa by spermagglutinating factor isolated from S. aureus with a high degree of specificity indicates receptor-ligand interaction. To examine this interaction we isolated and purified the ligand and the receptor. To assess receptor mediated agglutination of spermatozoa further we blocked spermagglutination induced by spermagglutinating factor in the presence of receptor. Spermagglutinating factor induced spermagglutination was competitively inhibited by adding purified receptor, indicating that sperm agglutinating factor isolated from S. aureus attaches to specific receptors on human spermatozoa. The spermagglutinating factor receptor was a protein with a molecular weight of approximately 57 kDa. Spermagglutinating factor induced spermagglutination and at higher concentrations had a spermicidal effect, which was inhibited by introducing the receptor. As observed on scanning electron microscopy studies, incubating spermatozoa with spermagglutinating factor showed profound morphological alterations. However, spermatozoa with normal morphology were noted when incubated with spermagglutinating factor in the presence of receptor, indicating that morphological alterations may account for spermatozoa agglutination by spermagglutinating factor. Results suggest that spermagglutinating factor isolated from S. aureus may bind specifically to sperm surface receptor sites before causing spermagglutination.