ISOLATION AND CHARACTERIZATION OF MONOCLONAL-ANTIBODIES SPECIFIC FOR THE EXTRACELLULAR DOMAIN OF PROSTATE-SPECIFIC MEMBRANE ANTIGEN

Purpose: Monoclonal antibodies specific for protein epitopes of prosta te specific membrane antigen (PSMA) expressed on the external surface of prostatic epithelial cells were prepared to provide material for us e in the diagnosis or treatment of prostatic cancer. Materials and Met hods: Mice were immunized with LNCaP cell membranes followed by purifi ed PSMA before fusion. Hybridomas were screened by reactivity with pur ified PSMA. Resulting antibodies were characterized by enzyme-linked i mmunosorbent assay, Western blot and fluorescence-activated cell sorte r analyses. Results: Monoclonal antibody producing hybridomas designat ed 3E11, 3C2, 4E10-1.14, 3C9 and 1G3 were obtained which displayed spe cificities for differing regions of the extracellular domain of the PS MA protein. These antibodies reacted strongly with PSMA from multiple sources and specifically stained unfixed PSMA expressing cells by flow cytometric analysis. Conclusions: The antibodies obtained displayed s trong reactivity and specificity for extracellular epitopes of PSMA Th ese antibodies will have value in future diagnostic and therapeutic ap plications focusing on PSMA as a target antigen.