An in-house ELISA assay for C1 inhibitor function via inhibition of kallikrein

Background: Bradykinin is the mediator responsible for local increase in vascular permeability hereditary angioedema (HAE; type I-II with low C1 inhibitor[C1-INH] level and/or function), and acquired (AAE). The current functional diagnostic assays employ complement inhibition, but there was no commercial physiological assay bradykinin pathway. Methods: We develop an ELISA using biotinylated kallikrein (enzyme of bradykinin-forming cascade) bound to avidin-coated plates. Incubation plasma followed by detection C1-INH. analysed data 120 healthy controls, 12 known HAE/AAE 31 bradykinin-unrelated disease. Reference range (≥45.0%) established. Accuracy, precision, linearity, limit blank, receiver operating curve (ROC) were used calculate performance assay. Results: function via inhibition significantly higher (p<0.0001) both subjects (75.3; 45.1–134.0%) diseased controls (87.6; 44.9–205.7%) when compared patients (14.9; 7.0–31.3%). Mixing test normal proved pathogenesis AAE. Agreement traditional chromogenic reached 96.1% (74/77). Calculations from ROC gave optimal cut-off (≥37.8%; area under curve/AUC 99.88%; sensitivity 100%, specificity 100% related clinical diagnosis). Conclusions: Our represents a tool diagnosis HAE It has potential role disease treatment response monitoring. References 1. Porebski Grzegorz, Kwitniewski Mateusz, Reshef Avner. Biomarkers angioedema. Clin Rev Allergy Immunol 2021; 60: 404–415. 2. Defendi Federica, Charignon Delphine, Ghannam Arije, et al. Enzymatic bradykinin-dependent PLoS One 2013; 8: e70140. 3. Kusumam J, Bains S, Tholanikunnel BG, A novel diagnose utilizing enzymes. 2015; 70: 115–119.