The journal of applied laboratory medicine
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The ubiquitously expressed dipeptidyl peptidase 3 (DPP3) is involved in protein metabolism, blood pressure regulation, and pain modulation. These diverse functions of DPP3 are attributed to the degradation of bioactive peptides like angiotensin II. However, because of limitations in currently available assays for determination of active DPP3 in plasma, the exact physiological function of DPP3 and its role in the catabolism of bioactive peptides is understudied. Here, we developed 2 assays to specifically detect and quantify DPP3 protein and activity in plasma and validated DPP3 quantification in samples from critically ill patients. ⋯ We developed 2 highly specific assays for the detection of DPP3 in plasma. These assays allow the use of DPP3 as a biomarker for the severity of acute clinical conditions and will be of great value for future investigations of DPP3's role in bioactive peptide degradation in general and the angiotensin II pathway in specific.