Acrosomal proteinase activity of human spermatozoa and relation of results to semen quality.

An assay for measuring the acrosomal proteinase activity of human spermatozoa with the use of a microscope slide coated with a thin layer of gelatin as a protein substrate was developed and applied to study the semen of 82 males from infertile couples and 15 normal donors. Acrosomal protease activity is indicated by a clear area of proteolyzed gelatin (halo) about the sperm head. Probit analysis revealed two populations divided at a halo diameter of 14 microns. The patient samples were grouped according to semen quality. The mean proteinase activity for most of the infertile groups was significantly below the control and more of the infertile men had a halo diameter less than 14 microns. Decreased activity was also found in 37% of patients with normal semen analysis. It is concluded that low acrosomal proteinase activity is associated with infertility. This reliable, inexpensive and rapid assay may prove to be helpful as an adjunct to semen analysis in the infertility work-up.