The characterization of human spermatozoa membrane proteins--surface antigens and immunological infertility

The aim of this study was to isolate and characterize highly enriched membrane proteins by two-dimensional (2-D) electrophoresis and to identify surface antigens binding sperm autoantibodies (SpAb). The presence of SpAb may reduce fertility by affecting sperm motility and acrosome reaction. The presence of the SpAb was shown to prevent sperm penetration of cervical mucus, to inhibit sperm-zona pellucida interaction, and to interfere with the sperm-egg fusion. The swim-up method was used to separate mature and motile sperm. Sperm membranes were obtained by hypoosmotic swelling, homogenization and sonication. Membranes were further isolated by differential centrifugation steps. The highly purified human sperm membrane proteins were separated by two-dimensional gel electrophoresis and electrotransferred to polyvinylidene difluoride (PVDF) membrane. The antigens were identified by bound SpAb, the sources of which were seminal plasma samples of infertile patients or of patients following vasectomy. Fourteen surface antigens were detected. Their identification may be (i) important for understanding the mechanism by which SpAb impair sperm fertilization capacity, (ii) suitable as a basis of new methods of fertility regulation, and (iii) helpful in developing reproducible and reliable methods for determinations of SpAb.