A high molecular weight antifertility factor from human seminal plasma

Abstract

The presence of a high MW antifertility factor [which may have relevance for clinical infertility studies] in human seminal plasma was established. The factor can be precipitated by centrifugation at 104,000 g. Its activity is maximal when the protein concentration reaches 150 .mu.g/105 spermatozoa using the mouse in-vitro fertilization assay as the test system. The factor is heat labile but its activity is not affected by dialysis. It prevents the spermatozoa penetration through the layers surrounding the egg but has no effect on spermatozoa/vitelline membrane fusion. The factor is only partly removed from spermatozoa by washing but is completely dispersed when the spermatozoa are incubated in capacitation medium. The pellet that is precipitated from the seminal plasma does not contain any particles or vesicles. It is significantly contaminated with low MW material. This material includes the acrosin inhibitor which is present in large enough quantities to hinder fertilization. Washing the pellet twice with H2O removes these low MW compounds, as indicated by acrosin inhibitor absence, but has no effect on pellet antifertility properties. Before further study or purification of the factor, it is essential that the pellet is washed to remove such low MW material. The washed pellet consists of at least 7 components as judged by disc gel electrophoresis.