Cleavage and inactivation of Factor IX by granulocyte elastase.

Abstract

A B S T R A C T Radioiodinated Factor IX was cleaved by a crude sonicate from leukocytes. In the absence of calcium, fragments of <15,000 mol wt were seen from reduced samples on gel electrophoresis. After digestion in 2 mM calcium, however, electrophoresis of reduced samples showed, in addition to low molecular weight fragments, protein bands corresponding in size to heavy and light chains of Factor XIa-activated Factor IX. The cleaving activity in leukocyte sonicates was inhibited by soybean trypsin inhibitor, but only to a small extent by aprotinin.Granulocyte elastase was isolated from purified polymorphonuclear leukocyte granules by affinity chromatography on soybean trypsin inhibitor-agarose and further chromatography on carboxymethyl cellulose. The purified fraction contained two isozymes on acidic gels which cleaved both an ester sensitive to elastase and radiolabeled Factor IX. These two activities were inhibited by elastase-specific chloromethyl ketone. The isolated protease fraction rapidly inactivated apparent Factor IX activity in a coagulant assay system. The degree of inactivation correlated with the amount of intact, radiolabeled Factor IX cleaved. As with the crude sonicate, generation of the larger heavy and light chain-sized fragments was dependent upon calcium.To assess directly the effect of elastase on Factor IX, an immunospecific, active site-directed assay was developed. In this assay, the sample was incubated with solid-phase antibody to Factor IX and the amount of activated product was detected as that which had com-

Rheological study on coagulation of blood with special reference to the triggering mechanism of venous thrombus formation

“…4, it was concluded that F-IXee possesses procoagulant activity J Biorheol (2009) 23:2- 10 5 when the degradation does not proceed to completion. This may not be contradictory to other reported results on leukocyte elastase, in which 30-40% of the initial coagulant activity remained after a 10 min incubation [27,30].…”

Proteolytic antibodies activate factor IX in patients with acquired hemophilia

“…Increased levels have recurrently been associated with thrombotic conditions. 23 In physiology, FIX is hydrolyzed and activated by activated FXI and by the tissue factor/activated FVII complex; it may be cleaved and inactivated by granulocyte and neutrophil elastase, 24,25 and by plasmin. 26 Our work identifies circulating IgG with proteolytic properties as novel molecules able to hydrolyze and activate FIX under pathologic conditions.…”

Changes in coagulation‐fibrinolysis marker and neutrophil elastase following the use of tourniquet during total knee arthroplasty and the influence of neutrophil elastase on thromboembolism

“…Neutrophil elastase is also known to inactivate various coagulation‐fibrinolysis factors in vitro (27–31), suggesting that NE may affect the coagulation‐fibrinolysis system as well. Thus, NE induces progressive inactivation of antithrombin III, which can lead to an almost complete loss of the thrombin inhibitory activity at a molar ratio of 1:1 (27).…”