< 0.5% cross-reactivity observed with available related molecules.< 50% cross-species reactivity observed with species tested.
No significant interference observed with available related molecules.
The Quantikine Human Cystatin B Immunoassay is a 4.5 hour solid phase ELISA designed to measure Cystatin B levels in cell culture supernates, serum, plasma, saliva, urine, and human milk. It contains E. coli-expressed recombinant human Cystatin B and antibodies raised against the recombinant protein. Results obtained for naturally occurring human Cystatin B and recombinant human Cystatin B showed linear curves that were parallel to the standard curves obtained using the Quantikine Human Cystatin B Immunoassay standards. These results indicate that this kit can be used to determine relative mass values for natural human Cystatin B.
Intra-Assay Precision (Precision within an assay) Three samples of known concentration were tested on one plate to assess intra-assay precision.
Inter-Assay Precision (Precision between assays) Three samples of known concentration were tested in separate assays to assess inter-assay precision.
The recovery of Cystatin B spiked to three different levels throughout the range of the assay in various matrices was evaluated.
Average % Recovery
Cell Culture Media (n=4)
EDTA Plasma (n=4)
Heparin Plasma (n=4)
To assess the linearity of the assay, samples containing high concentrations of Cystatin B were serially diluted with Calibrator Diluent to produce samples with values within the dynamic range of the assay.
Preparation and Storage
Store the unopened product at 2 - 8 °C. Do not use past expiration date.
Background: Cystatin B
Cystatin B, also known as Stefin B or liver thiol proteinase inhibitor, is a member of family 1 of the cystatin superfamily. It is a 98 amino acid, intracellular inhibitor regulating the activities of cysteine proteases of the papain family such as Cathepsins B, H and L.