The microtiter plate provided in this human IL-15 ELISA kit has been pre-coated with a monoclonal antibody specific to IL-15. Standards or samples supplied with this human IL-15 ELISA kit are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody preparation specific for IL-15 and incubated. IL-15 if present, will bind and become immobilized by the antibody pre-coated on the wells and then be “sandwiched” by biotin conjugate. The microtiter plate wells are thoroughly washed to remove unbound IL-15 and other components of the sample. In order to quantitatively determine the amount of IL-15 present in the sample, Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Avidin is a tetramer containing four identical subunits that each has a high affinity-binding site for biotin. The wells are thoroughly washed to remove all unbound HRP-conjugated Avidin and a TMB (3,3'5,5' tetramethyl-benzidine) substrate solution is added to each well. The enzyme (HRP) and substrate are allowed to react over a short incubation period. Only those wells that contain IL-15, biotin-conjugated antibody, and enzyme-conjugated Avidin will exhibit a change in colour. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the colour change is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm.

In order to measure the concentration of IL-15 in the samples, this human IL-15 ELISA 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-15 concentration (pg/mL). The concentration of IL-15 in the samples is then determined by comparing the O.D. of the samples to the standard curve. The minimum detectable quantities of human IL-15 human using this IL-15 ELISA kit are 10 pg/mL and 9 pg/mL, when use a standard curve generated with Calibrator Diluent I and Calibrator Diluent II, respectively. The two standard deviations above the mean optical density of the 20 replicates of the zero standard were defined as the minimum detectable quantities.

This human IL-15 ELISA kit is to be used for the in vitro quantitative determination of human interleukin 15 (IL-15) concentrations in serum, plasma, and cell culture supernatant. This sandwich human IL-15 ELISA kit can detect both natural and recombinant human IL-15. This kit exhibits no significant cross-reactivity with human IL-1, IL-2, IL-3, IL-4, IL-6, IL-7, IL-8, TNF-α, TNF-β, TGF-β1, TGF-β2, G-CSF, GM-CSF. This human IL-15 ELISA kit immunoassay is calibrated against natural human IL-15. (NIBSC/WHO First International Standard 95/554). This human IL-15 ELISA kit is intended FOR LABORATORY RESEARCH USE ONLY and is not for use in diagnostic or therapeutic procedures.

The biological activities of IL-15 are comparable to IL-2: IL-15 induces the proliferation of activated CD4-CD8-, CD4+CD8+, CD4+, and CD8+ cells and dendritic epidermal T cells. IL-15 co-stimulates proliferation of B cells activated with immobilized anti-human IgM or phorbol ester, but has no stimulatory effect on resting B cells. Maintenance of memory cells does not appear to require persistence of the original antigen; instead, survival signals for memory lymphocytes are provided by cytokines such as IL-15. In transgenic mice that have the IL-15 receptor alpha (IL-15Ralpha) gene knocked out, natural killer cells cells do not develop. In people with history of acute infectious mononucleosis (the syndrome associated with primary Epstein-Barr virus infection), IL-15R expressing lymphocytes are not detected--even 14 years after infection.