Human leukocyte elastase (HLE), also known as human neutrophil elastase, is a serine protease found abundantly in the azurophilic granules of the neutrophil as well as in monocytes and T cells that preferentially cleaves C-terminal of its substrates into small hydrophobic residues. Encoded by the ELA2 gene, HLE is a highly cationic glycoprotein (218 amino acids) characterized by containing four disulfide bridges and a conserved triad of amino acid residues, including His-41, Asp-88 and Ser-173, within the catalytic domain, which has been found to target a wide variety of substrates, including all components of the extracellular matrix, clotting factors, complement, immunoglobulins and cytokines.