Used to measure human neutrophil elastase (HLE) activity in biological samples such as serum, plasma, sputum, and cell culture supernatants. Commonly applied in research on inflammatory diseases including chronic obstructive pulmonary disease (COPD), cystic fibrosis, and acute lung injury. Helps assess the effectiveness of elastase inhibitors in drug development. Also used in studies of immune response and tissue remodeling where HLE plays a role in extracellular matrix degradation. Provides a sensitive and specific quantitative measurement, enabling accurate monitoring of disease progression and therapeutic intervention.