MONOCLONAL-ANTIBODIES TO TESTICULAR AUTOANTIGENS OF A TELEOST, THE NILE TILAPIA, OREOCHROMIS-NILOTICUS

In teleosts, several autoantigens, so-called sperm-specific antigens, are expressed on the germ cell surface during spermiogenesis and are thought to have sperm-specific functions. To investigate the functions of the autoantigens in Nile tilapia, Oreochromis niloticus, monoclonal antibodies to these polypeptides were produced. Balb/c mice were immunized with the autoantigens purified from the detergent-solubilized sperm protein by antisperm autoantibody affinity chromatography. Four hybridomas producing specific antibodies to the autoantigens were obtained. The monoclonal antibody, TAT (Testicular Antigen of Tilapia)-10 recognized a 27 kDa antigen. This antigen was localized in A and early B type of spermatogonia, spermatids in late spermiogenesis, and spermatozoa. This antigen was located primarily in the mid piece of the spermatozoa. Another antibody, TAT-20, recognized a 80 kDa polypeptide and another of about 40 kDa. TAT-21 recognized only a 80 kDa antigen. The antigens recognized by both TAT-20 and 21 were localized in spermatids in late spermiogenesis and in spermatozoa. TAT-30 reacted with a 120 kDa antigen which was localized in the epithelium of seminal ducts, Sertoli cells and spermatozoa. The antigens recognized by TAT-20, 21, and 30 were primarily on the head of spermatozoa. The possible functions of these autoantigens were discussed. (C) 1994 Wiley-Liss, Inc.