[Studies for development and clinical use of the simplified method of acrosin measurement by using gelatin substrate slides].

A simplified method for the detection of acrosin proteolytic activity (APA) of the individual sperm was developed by using a gelatin substrate slide. The following results were obtained in clinical application. Soybean trypsin inhibitor and TLCK completely inhibited APA at concentrations of 500 micrograms/ml and 1.5 mg/ml, respectedly. APA in diluted semen increased with greater dilution reaching the maximum at 8 to 10 fold dilution. Even at this dilution, APA was only 70% of the APA measured with washed sperm. A significant correlation was found between APA and the sperm concentration in male infertility. APA increased as the concentration of sperm increased, and the lowest APA was observed at less than 20 X 10(6)/ml. An unexplained male infertility group had a significantly lower APA than a fertile group. The group with both more than 40% motility and 2b quality had a higher APA than other groups with poor motility. There was no significant correlation between the rate of penetration of the zona-free hamster ova seen in the penetration assay and APA. Sperm-immobilizing antibody had no effect on APA. Nonoxynol-9 (N-9), a spermicidal agent, could inhibit APA completely at concentrations of 250 micrograms/ml and more. A linear regression curve of APA was obtained with a log-dose concentration of N-9. From these results it is felt that this newly developed method will be useful in clinical practice.