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IL-33

Interleukin-1 (IL-1) family members, such as IL-1α/β and IL-18 play important roles in host defense, immune regulation, neuronal injury and inflammation (1, 2). Recently, a new member of this family, IL-33, also named Nuclear Factor from High Endothelial Venules (NF-HEV) (3), has been reported to be the specific ligand for ST2 (4), an orphan receptor of the IL-1 receptor family (5). Structurally, IL-33 is closest to IL-18, rather than IL-1β. The human IL-33 is expressed with a prodomain (aa 1-111) that is cleaved by caspase-1 to produce a 18kDa mature protein (112-270) (6). The stimulation of ST2 by IL-33 induces the NF-κB and MAPK pathways. IL-33 is synthesized in response to cytokines such as IL-1β (but also TNFα) and plays an important role in T_H2-associated immunology, by triggering an increase secretion of IL-5 and IL-13 from polarized T_H2 cells. Overexpression of IL-33 in mice leads to severe pathological changes in mucosal organs.

IL-33, Soluble (human) Detection Set (APO-54N-025)

Summary of features

	For the quantitative determination of soluble human IL-33 from biological fluids (serum and cell culture supernatant)
	Detection based on a Sandwich ELISA
	Detection limit: 5 pg/ml
	Range: 7.8 pg-500 pg/ml
	Specificity : Detects only human IL-33
	Format: sufficient materials to run ELISAs on 5 x 96-well plates

Principle of the Kit

This assay is a sandwich Enzyme Linked-Immuno-Sorbent Assay (ELISA) developed for the direct measurement of human IL-33 (hIL-33) in biological fluids. A polyclonal antibody specific for hIL-33 (COAT) is coated onto the wells of the microtiter plate. Samples and standards of hIL-33 are pipetted into the wells for binding to the coated antibody. After extensive washing to remove unbound compounds, hIL-33 is recognized by the addition of a biotinylated monoclonal antibody specific for hIL-33 (DET). After removal of excess biotinylated antibody, streptavidine-peroxidase is added. Following a final washing, peroxidase activity is quantified using the substrate 3,3’,5,5’-tetramethylbenzidine (TMB). The intensity of the color reaction is measured at 450 nm after acidification and is directly proportional to the concentration of hIL-33 in the samples.

Figure: Linearity of the STD curve.

LITERATURE OVERVIEW:

1. Lee, J. K. et al. Differences in signaling pathways by IL-1beta and IL-18. Proc Natl Acad Sci U S A 101, 8815-20 (2004).

2. Allan, S. M., Tyrrell, P. J. & Rothwell, N. J. Interleukin-1 and neuronal injury. Nat Rev Immunol 5, 629-40 (2005).

3. Brint, E. K. et al. ST2 is an inhibitor of interleukin 1 receptor and Toll-like receptor 4 signaling and maintains endotoxin tolerance. Nat Immunol 5, 373-9 (2004).

4. Schmitz, J. et al. IL-33, an interleukin-1-like cytokine that signals via the IL-1 receptor-related protein ST2 and induces T helper type 2-associated cytokines. Immunity 23, 479-90 (2005).

5. Martinon, F. & Tschopp, J. Inflammatory caspases: linking an intracellular innate immune system to autoinflammatory diseases. Cell 117, 561-74 (2004).

6. Baekkevold, E. S. et al. Molecular characterization of NF-HEV, a nuclear factor preferentially expressed in human high endothelial venules. Am J Pathol 163, 69-79 (2003).