Immunochemical localization and characterization of proteins from mouse cauda epididymis using human sperm specific...

Monoclonal antibodies (mAbs) to sperm specific antigens were generated by fusion of mouse myeloma cells (SP2/0) with splenocytes of female BALB/c mice hyperimmunized with washed human spermatozoa. The resultant hybridomas producing antisperm antibodies were first screened by ELISA. Out of these, one of the mAbs (D2G4) which recognized target antigens restricted to the acrosomal cap was chosen for these studies. The mAb D2G4 was found to be an agglutinating antibody and was also found to cross-react with mouse epididymal spermatozoa in ELISA and indirect immunofluorescence. The origin of antigens reacting with monoclonal antibody D2G4 was investigated. When frozen sections of murine testis and various regions of epididymis were reacted with mAb D2G4, only the cauda epididymal region was stained. Western blot of proteins from the epididymal spermatozoa and fluid indicated the presence of two bands of mol. wt 45 and 26 kd. These bands were identical under reducing and non-reducing conditions. These observations suggest that the two proteins are structurally similar or at least have a common epitope. These data indicate that the proteins recognized by D2G4 are acquired by spermatozoa during their passage and storage in the cauda epididymis.