The fate of acrosomal staining during the acrosome reaction of human spermatozoa as revealed by a monoclonal antibody and PNA‐lectin

Abstract

A monoclonal anti‐human sperm antibody, raised against an acrosomal antigen and indicated to recognize in boar sperm the serine protease, acrosin, stained in human spermatozoa a 50 Kd antigen and several others in the region 24–34 Kd by immunoblotting. The 50 Kd band and the region of 30–34 Kd showed proteolytic activity by zymographic enzyme detection. The fate of the antigen was studied in the acrosome reaction induced by the calcium ionophore A23187. In control incubations 69.5 ± 14.2% (mean ± SD) of the spermatozoa had intact acrosomal staining according to indirect immunofluorescence using this antibody whereas in acrosome‐reacted samples only 21.0 ± 2.0% of the sperm were stained. Another marker for the acrosome, peanut agglutinin‐lectin (PNA), was used to detect the acrosome with similar results. Acrosome reactions were verified by electron microscopy. The present results indicate that the corresponding antigen, evidently acrosin, and PNA‐positive material are liberated during the acrosome reaction which suggests that they are not bound to the inner acrosomal membrane but are components of the acrosomal matrix. Copyright © 1986, Wiley Blackwell. All rights reserved