A monoclonal antibody (ST-1) directed to the native heparin chain

A mouse monoclonal antibody, ST-1, was raised against heparin complexed to Salmonella minnesota. Characterization of this antibody showed that it recognizes an epitope in the intact molecule of heparin that is present regardless of its source or anticoagulant activity. ST-1 is the first monoclonal antibody specific for the intact unmodified molecule of heparin to be described. 3H-labeled heparin in solution was immunoprecipitated by ST-1, and the formation of the 3H-labeled immunocomplex was selectively inhibited by unlabeled heparin. No cross-reactivity of ST-1 was observed with other glycosaminoglycans such as heparan sulfate, chondroitin sulfate, hyaluronic acid, dermatan sulfate, and keratan sulfate, or with polyanionic polymers such as dextran sulfate. Selective removal of the N-sulfate groups or N,O-desulfation of heparin strongly reduced the binding of ST-1. Inhibition of binding was also observed after carbodiimide reduction of the carboxyl groups of the uronic acid units of heparin. Competitive assays of ST-1 binding to heparin immobilized on poly-L-lysine-coated plates using oligosaccharides of different sizes that arose from HNO2 cleavage of heparin showed that the minimum fragment required for reactivity of ST-1 is a decasaccharide.