< 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 FABP4 Immunoassay is a 4.5 hour solid-phase ELISA designed to measure human FABP4 in cell culture supernates, cell lysates, serum, and plasma. It contains E.
coli-expressed recombinant human FABP4 and has been shown to accurately quantitate the recombinant factor. Results obtained using natural human FABP4 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 FABP4.
Intra-Assay Precision (Precision within an assay) Three samples of known concentration were tested twenty times on one plate to assess intra-assay precision.
Inter-Assay Precision (Precision between assays) Three samples of known concentration were tested in twenty separate assays to assess inter-assay precision. Assays were performed by at least three technicians using two lots of components.
The recovery of human FABP4 spiked to levels throughout the range of the assay in various matrices was evaluated.
Average % Recovery
Cell Culture Media (n=4)
Cell Lysis Buffer 1 (n=2)
EDTA Plasma (n=4)
Heparin Plasma (n=4)
To assess the linearity of the assay, samples containing and/or spiked with high concentrations of human FABP4 were 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.
FABP4 (Fatty Acid Binding Protein 4), also known as A-FABP and aP2, is the predominant FABP found in adipocytes and is often used as a marker for adipocyte differentiation. It is also expressed in macrophages, dendritic cells, and endothelial cells. FABP4 is a key mediator of intracellular fatty acid transport and metabolism in adipose tissue. Its expression is regulated by multiple factors including fatty acids, PPAR gamma agonists, and Insulin, and its levels increase with lipolytic stimulation. It can increase the hydrolytic activity of Hormone-Sensitive Lipase and increase the production of proinflammatory cytokines and chemokines. FABP4 upregulation in adipocytes and macrophages is associated with the development of Insulin resistance, hypertriacylglycerolaemia, and atherosclerosis. Serum levels of FABP4 are elevated in obesity and metabolic syndrome, type 2 diabetes, HIV-associated lipodystrophy, polycystic ovary syndrome, nonalcoholic fatty liver disease, atherosclerosis, and acute ischaemic stroke. FABP4 is also overexpressed in multiple cancer types including ovarian, bladder, glioblastoma, and oral, and it may play a role in tumor progression.
Refer to the product for complete assay procedure.
Bring all 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 room temperature for 2 hours.
Aspirate each well and wash, repeating the process 3 times for a total of 4 washes.
200 µL Conjugate
Add 200 µL of Conjugate to each well. Cover with a new plate sealer, and incubate at room temperature for 2 hours.
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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