Preparation and characterization of monoclonal antibodies against pseudexin

Fifteen hybridoma cell lines secreting monoclonal antibodies against pseudexin were developed. The cell lines were grown as ascites tumors and the resulting antibodies were purified by Protein A affinity-chromatography. Several of the antibodies exhibited extensive ELISA cross-reactions with different phospholipase A2 toxins from various snake venoms, while other of the antibodies reacted only with the pseudexins. Three of the antibodies neutralized pseudexin A and B, but none of the 10 other phospholipase A2 toxins tested. These same three antibodies inhibited the enzymatic activity of pseudexin A and B and also that of notexin. After each antibody was labeled with biotin, competition experiments were carried out to determine the binding relationships among the antibodies and the pseudexins. Competitions were frequently observed, with a low of zero to a high of eight out of the 14 possibilities. Competition experiments were also carried out with biotin-labeled rabbit IgG against the pseudexins. Some of the monoclonal antibodies had no effect on rabbit IgG binding to pseudexin, while others blocked up to 50% of the binding.