Serine Protease Generation by Oversulfated Chondroitin Sulfate and Contaminants in Heparin: Clinical Implications

Abstract

We hypothesized that Oversulfated Chondroitin Sulfate (OSCS) and the other contaminants present in contaminated heparin may mediate the generation of several serine proteases. To address this hypothesis, seven batches of recalled heparins linked to adverse patient outcomes were supplemented to freshly drawn, normal human plasma anti‐coagulated with hirudin. The generation of markers of an immune reaction, as well as rate of formation of these enzymes, was measured in biochemically defined assay conditions using chromophore‐conjugated substrates for Kallikrein, Plasma Kininogenase, C1 esterase, Thrombin, Xa and Plasmin. Assays performed with substrates for Kallikrein, Plasma Kininogenase, and C1 esterase showed a time‐dependent generation of these proteases that was strongest in the samples containing purified contaminant OSCS. Of the six contaminated heparins, four preparations showed a strong activation of these proteases which were significantly different (p<0.050) than the control non‐contaminated heparins. Our studies suggest that heparin contaminants are capable of activating multiple serine proteases, which potentially contribute to the pathogenesis of observed adverse clinical events. Classical complement pathway activation is not suggested by this data as a significant increase in C1 esterase activity is noted with all heparins, including purified OSCS.