Detection using antisperm monoclonal antibodies of shared epitopes expressed by human spermatozoa and oocytes.
OBJECTIVE: To determine whether human spermatozoa and oocytes share common antigenic epitopes, supporting the hypothesis that their cross-linking by antisperm antibodies present in the clinical sera of infertile couples could promote sperm adhesion to the oolemma. DESIGN: Human and hamster eggs were studied for the presence of antigens recognized by a panel of World Health Organization Task Force monoclonal antibodies (mAbs) originally raised against human spermatozoa. A new technique was devised, using frozen sections of paraformaldehyde-fixed individual human and hamster eggs, to screen rapidly antisperm mAbs for egg reactivity. Living zona-free human and hamster eggs then were exposed to Covaspheres (Duke Scientific, Palo Alto, CA) coupled with these mAbs to document the presence of reactive epitopes on the oolemma. SETTING: Academic research environment. MAIN OUTCOME MEASURE(S): Indirect immunofluorescence and Covasphere rosetting. RESULT(S): Eleven of 37 antisperm mAbs tested reacted with fixed hamster eggs and 10 reacted with human eggs. Five of 6 mAbs reactive with both fixed eggs also reacted with the oolemma of living, zona-free eggs. CONCLUSION(S): Common antigenic epitopes, some of which are shared with somatic tissues, exist on the oolemma of human eggs and on the plasma membrane of human spermatozoa.