Used to measure purine nucleoside phosphorylase (PNP) activity in human biological samples such as serum, plasma, or cell lysates. This ELISA kit is commonly applied in clinical research and immunology studies to assess immune system function, as PNP plays a key role in purine metabolism and T-cell regulation. It is also used in diagnosing and monitoring PNP deficiency, a rare genetic disorder linked to severe combined immunodeficiency (SCID). Researchers use this kit to evaluate PNP levels in studies related to autoimmune diseases, cancer, and drug development targeting purine metabolism pathways. The assay provides a sensitive and specific quantitative measurement, enabling high-throughput analysis in laboratory settings.