Human Cystatin 3 ELISA Kit

A sandwich enzyme-linked immunosorbent assay (sELISA) manufactured by Antibodies.com as part of their Assays and Kits range, intended for the in vitro quantitative determination of human Cystatin C. Acceptable sample types include serum, plasma, tissue homogenates, cell lysates, cell culture supernates or other biological fluids. Synonyms listed for the target include CST3, Cystatin-3, Gamma-trace, Neuroendocrine basic polypeptide and Post-gamma-globulin.

The assay employs a 96-well microtiter plate pre-coated with an antibody specific for Cystatin C. Standards and test samples are added to the wells and captured by the immobilised antibody; after washing, a biotinylated anti-Cystatin C detection antibody is added, followed by HRP-avidin conjugate and TMB substrate. The HRP-catalysed reaction yields a blue product that converts to yellow upon addition of acidic stop solution. Absorbance is read at 450 nm in a colorimetric microplate reader, and the concentration of Cystatin C is calculated against the standard curve.

Reported performance includes a product range of 1.56–100 ng/ml and a sensitivity of <0.64 ng/ml, with a total assay time of 4 hours 30 minutes. Manufacturer spike-and-recovery data showed an average recovery of 91% in serum (n=5, range 80–102%), 90% in EDTA plasma (n=5, range 81–100%) and 84% in heparin plasma (n=5, range 80–89%). Dilution linearity across 1:2, 1:4, 1:8 and 1:16 dilutions yielded recoveries of 87–91%, 87–107%, 74–101% and 92–97% in serum; 90–105%, 84–101%, 90–101% and 79–108% in EDTA plasma; and 84–95%, 92–105%, 82–105% and 89–91% in heparin plasma (n=5 for each matrix). Kit components are to be stored at +4°C or -20°C as instructed, and the kit is not to be used past its expiration date.