Monoclonal Antibodies against Heparin and Heparinoids

 

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Abstract

The antigenicity of glycosaminoglycans and galactosaminoglycans is very weak. Accordingly, only a few reports on the successful production of monoclonal antibodies against glycosaminoglycans and galactosaminoglycans have been published. Antibodies have been raised against the heparinlike compounds heparan sulfate,^1,2 chondroitin sulfate,³ and keratan sulfate.^4,5 The production of heparin antibodies was reported.^6-8 But further analysis showed that the antibodies were not directed against native heparin but against heparin conjugates or chemically modified heparins.

After immunization with a heparin-bovine serum albumin conjugate, prepared by reductive amination, a monoclonal antibody against heparin and heparin fractions was obtained (Huhle et al: Semin Thromb Hemostas 20:193-204, 1995). For further analysis, tyramine, which was covalently bound to low-molecular-mass heparin (LMMH) by endpoint attachment (Malsch et al: Anal Biochem 217:255-264, 1994), was labeled with iodine-125 at the aryl residue. The tracer antibody complex was immunoprecipitated by goat anti-mouse immunoglobulin IgG. H1.18 recognized specifically intact heparin and heparin fractions. The lower detection limit for heparin preparations was 100 ng/mL. The H1.18 antibody was purified by ammonium sulfate precipitation. H1.18 remained biologically and functionally active after purification. The smallest disaccharide that was detected by H1.18 was found to be iduronic acid-anhydromannose, obtained by nitrous acid degradation of LMMH. Endpoint attachment of tyramine to anhydromannose did not modify the binding of the disaccharide to H1.18, indicating the importance of iduronic acid for binding of glycosaminoglycans to the antibody.