The Quantikine Human Cystatin C Immunoassay is a 4.5 hour solid-phase ELISA designed to measure human Cystatin C in cell culture supernates, serum, plasma, saliva, urine, and human milk. It contains NS0-expressed recombinant human Cystatin C and has been shown to accurately quantitate the recombinant factor. Results obtained using natural human Cystatin C showed linear curves that were parallel to the standard curves obtained using the Quantikine kit standards. These results indicate that this kit can be used to determine relative mass values for naturally occurring human Cystatin C.
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 C spiked to levels throughout the range of the assay was evaluated.
Average % Recovery
Cell Culture Media (n=4)
To assess the linearity of the assay, samples containing high concentrations of Cystatin C were serially diluted with the 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 C
Cystatin C is a secreted cysteine protease inhibitor that inhibits Cathepsins B, H, K, L, and S. Cystatin C serum concentration correlates closely to the glomerular filtration rate (GFR); elevated levels are associated with coronary artery and cardiovascular disease risk. Dysregulation of Cystatin C can modulate tumor growth and metastasis. In humans, the L68Q variant forms dimers and oligomers more easily than wild type protein and is the cause for hereditary Cystatin C amyloid angiopathy.
Refer to the product for complete assay procedure.
The conjugate must remain at 2-8 °C during use. Bring all other reagents and samples to room temperature before use. It is recommended that all samples, standards, and controls be assayed in duplicate.
Prepare all reagents, standard dilutions, and samples as directed in the product insert.
Remove excess microplate strips from the plate frame, return them to the foil pouch containing the desiccant pack, and reseal.
100 µL Assay Diluent
Add 100 µL of Assay Diluent to each well.
50 µL Standard, Control, or Sample
Add 50 µL of Standard, control, or sample to each well. Cover with a plate sealer, and incubate at 2-8 °C for 3 hours.
Aspirate each well and wash, repeating the process 3 times for a total of 4 washes.
200 µL cold Conjugate
Add 200 µL of cold Conjugate to each well. Cover with a new plate sealer, and incubate at 2-8 °C for 1 hour.
Aspirate and wash 4 times.
200 µL Substrate Solution
Add 200 µL Substrate Solution to each well. Incubate at room temperature for 30 minutes. PROTECT FROM LIGHT.
50 µL Stop Solution
Add 50 µL of Stop Solution to each well. Read at 450 nm within 30 minutes. Set wavelength correction to 540 nm or 570 nm.
R&D Systems personnel manually curate a database that contains references using R&D Systems products.
The data collected includes not only links to publications in PubMed,
but also provides information about sample types, species, and experimental conditions.
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