Circulating heparan sulfate anticoagulant in a patient with a fatal bleeding disorder.

We have identified a circulating, heparin-like anticoagulant in a patient with multiple myeloma (IgG4 lambda) who had serious clinically evident bleeding that contributed to his death. Purification of the patient's circulating coagulation inhibitor was accomplished by ammonium sulfate concentration, anion exchange chromatography, and affinity chromatography on protamine sulfate. Analysis of the purified inhibitor showed that it was a proteoglycan that comigrated with heparan sulfate on lithium acetate-agarose-gel electrophoresis and that it contained 39 per cent L-iduronic acid. Control samples of heparan sulfate and heparin contained 29 and 68 per cent L-iduronic acid, respectively. Functional coagulation studies revealed that the purified inhibitor had cofactor activity with antithrombin III that could be abolished by prior incubation with protamine sulfate or platelet factor 4. Recognition of the existence of this or of other similar inhibitors in bleeding patients is important because of the potential for treatment with agents such as protamine sulfate and platelet factor 4, which neutralize the anticoagulant effects of proteoglycans.