Monoclonal Antibodies as Direct Probes for Human Sperm Acrosome Reaction

PROBLEM: To develop simple and rapid assay procedures for determining human sperm acrosome reaction under various experimental conditions. METHODS: Specific monoclonal antibodies against human sperm acrosome were generated and utilized as probes for acrosome reaction assays by direct labelling of antibodies with fluorescein‐isothiocyanate (FITC). RESULTS: Among the generated monoclonal antibodies, HS‐63 was shown to react with antigens in the acrosome content of permeabilized acrosome‐intact human sperm, but not with those of the live ones. HSA‐10 was found to recognize antigens on the surface of sperm inner acrosome and to react with acrosome‐reacted human sperm in suspension. Following a swim‐up procedure, highly motile sperm were recovered and incubated in BWW medium at 37°C for 18 h. The percentages of acrosome‐reacted sperm were determined at various incubation times by using FITC‐labeled HS‐63 or HSA‐10 as the indicators in 10 min direct immunofluorescent assay. With the FITC‐labeled HS‐63 probe, the percentage of positively stained human sperm fixed in methanol decreased significantly after 18 h of incubation from >90 to 70–80%. In contrast, positively stained live human sperm by HSA‐10 increased significantly from