Antibody against 28-kDa intra-acrosomal sperm protein as a tool for evaluation of acrosomal integrity in bull spermatozoa.

Monoclonal antibody ACR.4 recognizing specifically the 28-kDa intra-acrosomal protein was prepared by immunization of mice with acetic acid extract of boar spermatozoa, but cross-reacted also with bull intra-acrosomal protein. This monoclonal antibody was used for immunostaining analysis of bull spermatozoa before and during capacitation and ionophore-induced acrosome reaction. Immunostaining analysis showed changes of 28-kDa protein in the acrosome during capacitation and loss of this protein after induced acrosome reaction by ionophore A23187. Therefore, this monoclonal antibody can be used in the bull spermatozoa as an immunological test for detection of the acrosome state after manipulation with spermatozoa or after freezing/thawing. This test could be useful (apart from morphology and motility) for the selection of suitable spermatozoa for insemination or in vitro fertilization.