Human TNF-alpha Quantikine ELISA Kit Summary

Product Summary

The Quantikine Human TNF-alpha Immunoassay is a 4.5 hour solid phase ELISA designed to measure human TNF-alpha in cell culture supernates, serum, and plasma. It contains E. coli-derived recombinant human TNF-alpha and antibodies raised against this protein. It has been shown to accurately quantitate the recombinant factor. Results obtained with naturally occurring TNF-alpha samples 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 natural human TNF-alpha.

Preparation and Storage

Background: TNF-alpha

Tumor necrosis factor alpha (TNF-α), also known as cachectin and TNFSF2, is the prototypic ligand of the TNF superfamily. It is a pleiotropic molecule that plays a central role in inflammation, apoptosis, and immune system development. TNF-α is produced by a wide variety of immune and epithelial cell types. Human TNF-α consists of a 35 amino acid (aa) cytoplasmic domain, a 21 aa transmembrane segment, and a 177 aa extracellular domain (ECD). Within the ECD, human TNF-α shares 97% aa sequence identity with rhesus and 71% - 92% with bovine, canine, cotton rat, equine, feline, mouse, porcine, and rat TNF-α. The 26 kDa type 2 transmembrane protein is assembled intracellularly to form a noncovalently linked homotrimer. Ligation of this complex induces reverse signaling that promotes lymphocyte costimulation but diminishes monocyte responsiveness.

Cleavage of membrane bound TNF-α by TACE/ADAM17 releases a 55 kDa soluble trimeric form of TNF-α. TNF-α trimers bind the ubiquitous TNF RI and the hematopoietic cell-restricted TNF RII, both of which are also expressed as homotrimers. TNF-α regulates lymphoid tissue development through control of apoptosis. It also promotes inflammatory responses by inducing the activation of vascular endothelial cells and macrophages. TNF-α is a key cytokine in the development of several inflammatory disorders. It contributes to the development of type 2 diabetes through its effects on insulin resistance and fatty acid metabolism.

Assay Procedure

Refer to the product datasheet for the 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.

1.     Prepare all reagents, standard dilutions, and samples as directed in the product insert.

2.     Remove excess microplate strips from the plate frame, return them to the foil pouch containing the desiccant pack, and reseal.

3.     Add 50 μL of Assay Diluent to each well.

4.     Add 50 μL of Standard, control, or sample to each well. Cover with a plate sealer, and incubate at room temperature for 2 hours.

5.     Aspirate each well and wash, repeating the process 4 times for a total of 5 washes.

6.     Add 100 μL of Conjugate to each well. Cover with a new plate sealer, and incubate at room temperature for 2 hours.

7.     Aspirate and wash 5 times.

8.     Add 100 μL Substrate Solution to each well.

9.     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.