Interleukin 16, Human (LCF, prIL-16, FLJ16806, FLJ42735, FLJ44234, HST19289 ) BioAssay(TM) ELISA Kit

Introduction:\nInterleukin-16 (IL-16) discovered in 19821, known formerly as lymphocyte chemoattractant factor (LCF) is a lymphocyte chemoattractant factor of T cell origin with selective activity for CD4+ T cells. LCF was designated interleukin-16 (IL-16) in 1995. IL-16 is a product of CD8+ cells, CD4+ cells2, eosinophils3, mast cells and epithelial cells derived from asthmatics4. Expression of IL-16 in asthmatic epithelium correlates with the number of infiltrating CD4+ T cells5. \n\nLCF was originally identified and purified from the supernatants of ConA-stimulated peripheral blood mononuclear cells (PBMC). In addition to its chemotactic activity, it is a competence growth factor selective for CD4+ T cells dependent on an interaction with CD4 for induction of functional activity. Its cDNA codes for a novel 14-kD protein into a homotetrameric form is required for induction of biologic activity. IL-16 appears in culture supernatants as a relative molecular mass (Mr) ~56,000 biologically active, non-covalently linked tetramer, but migrates in monomeric form in SDS PAGE. Eluted monomeric peptides are inactive but reaggregate to Mr 56,000 regaining biological activity6. The protein expressed from the IL-16 cDNA demonstrates all the functions and chemical features of the native protein, including an identical pI, and autoaggregation into functional tetramers.\n\nIL-16 is preformed and stored in biologically active form in CD8+. T cells from which it is secreted following stimulation with histamine via H2 type receptors. The secretory process occurs within 4 hrs and does not require transcription, translation, or new protein synthesis.\n\nIL-16пїЅs ability to inhibit the MLR and other antigen induced activation suggests that it may be useful in inhibiting allograft rejection. Because IL-16 selectively induces IL-2 responsiveness in CD4+ T cells it may be useful (along with IL-2) for selective CD4+ T cell immune reconstitution in individuals with lymphopenia, for example following chemotherapy or HIV-1 infection. In the latter circumstance, its ability to inhibit HIV transcription should provide a protective role if used as a therapy in HIV-1 infected individuals7. \n\nInhibitors of IL-16 chemotactic function may be useful in diseases in which it appears to play a prominent role in the inflammatory process. The presence of IL-16 early after antigen challenge in asthma8, the marked upregulation of IL-16 synthesis by epithelium of asthmatics along with the correlation of IL-16 protein with the number of infiltrating CD4+ T cells in the airways of human asthmatics suggest that therapeutics aims at blocking IL-16 synthesis or function may be valuable in this disease.\n\nThis IL-16 ELISA is a 4.5 hour solid phase immunoassay readily applicable to measure IL-16 in serum, plasma, cell culture supernatant, and other biological fluids in the range of 0 to 3200pg/ml. It showed no cross-reactivity with other cytokines tested such as EGF, EPO, GM-CSF, IL-1b, IL-7, IL-8, IFN-g, MCAF, MCP-3, M-CSF, SAA, TGF-b, and TNF-a.\n\nPrinciple of the Assay:\nThis IL-16 enzyme-linked immunosorbent assay (ELISA) applies a technique called a quantitative sandwich immunoassay. The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for IL-16. Standards or samples are then added to the appropriate microtiter plate wells and incubated. IL-16 if present, will bind and become immobilized by the antibody pre-coated on the wells. The microtiter plate wells are thoroughly washed to remove any unbound IL-16 and other components of sample. In order to quantitate the amount of IL-16 present in the sample, a standardized preparation of horseradish peroxidase (HRP)-conjugated polyclonal antibody specific for IL-16 is added to each well to "sandwich" the IL-16 immobilized during the first incubation. The microtiter plate then undergoes a second incubation. The wells are thoroughly washed to remove all unbound HRP-conjugated antibodies and a TMB (3,3'5,5' tetramethyl-benzidine) substrate solution is added to each well. The enzyme (HRP) and substrate solution are allowed to react over a short incubation period. Only those wells that contain IL-16 and enzyme-substrate reaction will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of sulphuric acid solution and the color change measured spectrophotometrically at a wavelength of 450nm пїЅ 2nm. \n\nIn order to measure the concentration of IL-16 in the samples, this kit includes two calibration diluents (Calibrator Diluent I for serum/plasma testing and Calibrator Diluent II for cell culture supernatant testing). According to the testing system, the provided standard is diluted (2-fold) with the appropriate Calibrator Diluent and assayed at the same time as the samples. This allows the operator to produce a standard curve of Optical Density (O.D) versus IL-16 (pg/ml). The concentration of IL-16 in the samples is then determined by comparing the O.D. of the samples to the standard curve.\n\nKit Components:\n1. IL-16 Microtiter Plate, 1x96 wells \n2. IL-16 Conjugate, 1x25ml \n3. IL-16 Standard, 2x1 vials\n4. Calibrator Diluent I, 1x 30ml \n5. Calibrator Diluent II, 1x 50ml \n6. Wash Buffer (20X), 1x 60ml \n7. Substrate A, 1x16ml \n8. Substrate B, 1x16ml \n9. Stop Solution, 1x14ml, 2N Sulphuric Acid (H2SO4). \n\nSensitivity: <20ng/ml\n\nRange: 20-3200ng/ml\n\nStorage and Stabilty:\nStore components at -20 degrees C. Stable for 6 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.пїЅ

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SPECIFICATIONS

Catalog Number

I8438-04

Size

96Tests

Applications

ELISA

References

1. Center, D.M. et al. (1982) J. Immunol. 128: 2563-2568.\n2. Laberge, S. et al. (1995) J. Immunol. 55: 2902-2910.\n3. Lim, K. et al. (1996) J. Immunol. 156: 2566-2570.\n4. Bellini, A. et al. (1993) J. All. Clin. Immunol. 92: 412-424.\n5. Laberge, S. et al. (1997) Am. J. Resp. Cell Mol. Biol. 17(2): 193-202.\n6. Cruikshank, W. et al., (1997) J. Immunol. 128: 2569-2571.\n7. Center, D. M. et al. (1997) Int. J. Biochem. Cell Biol. 29: 1231-1234.\n8. Cruikshank, W. et al (1995) Am. J. Resp. Cell Mol. Biol. 13: 738-747.\n