Leukocyte Elastase Release during Blood Coagulation

Abstract

A B S T R A C T Immunological detection of elastase, an enzyme present within leukocyte granules, has been used as a marker for polymorphonuclear leukocyte activation. Polymorphonuclear leukocytes contained 4.6 gg/107 cells, whereas erythrocytes, mononuclear cells, and platelets contained < 1% of this level. In plasma that was separated from blood cells after 1 h at 22°C, the mean level of elastase-related antigen in seven normal donors was 25±6 ng/ml. This level was unaltered by immediate separation of the plasma from the cells, by inclusion of protease inhibitors, or by anticoagulation of the plasma with either EDTA or acidcitrate-dextrose (the level in heparinized plasma was approximately threefold higher). In serum, the level of elastase-related antigen was 288±125 ng/ml, representing an 11.5-fold increase above plasma levels. The antigen detected in serum was immunochemically indistinguishable from the leukocyte enzyme. Release of elastase was observed when isolated polymorphonuclear leukocytes were added to nonanticoagulated platelet-rich or platelet-poor plasma, recalcified plasma, or to serum. Addition of a chelating agent to serum prevented elastase release, but calcium or magnesium did not induce release in the absence of plasma. Coagulation induced by addition of thrombin to plasma also failed to induce release. In whole blood or in anticoagulated plasma reconstituted with polymorphonuclear leukocytes and then recalcified, initial release of elastase occurred concomitantly with or slightly after clotting and reached maximal levels within 20-40 min after clot formation. The data indicates that early events in coagulation or other pathways that occur in parallel with coagulation induce leukocyte release. The release of elastase, a major fibrinolytic protease of leukocytes, from the cells provides a mechanism Portions of this study were presented at the

Leukocyte proteases cleave von Willebrand factor at or near the ADAMTS13 cleavage site

“…Indeed, serum elastase concentrations are nearly 7-fold higher than citrateor EDTA-anticoagulated plasma elastase levels. 35 Clinical observations also support a possible role of leukocytes in down-regulating VWF. For example, high neutrophil counts have been associated with VWF proteolysis in acute promyelocytic leukemia.…”

“PMN-Elastase Assay”: Enzyme Immunoassay for Human Polymorphonuclear Elastase Complexed with α1-Proteinase Inhibitor

“…Plasma was separated from blood within 30 min after sample collection to prevent interference by in vitro secretion by leukocytes (15,16). Tests were performed either on fresh plasma or on aliquots stored frozen at -20 °C or -70 °C.…”

Local abnormalities in coagulation and fibrinolytic pathways predispose to alveolar fibrin deposition in the adult respiratory distress syndrome.

“…Coagulation and extravascular fibrin may liberate cleavage products which are capable of potentiating the acute inflammatory response via effects on chemotaxis, vascular permeability, and immunomodulation (4-9). Activation of coagulation or fibrinolysis may, in turn, activate complement (10, 1 1), kinin-forming pathways (12), and release of neutrophil elastase (12,13). In addition, fibrin deposits may influence the reparative response to acute lung injury.…”