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HUMAN SOLUBLE INTERLEUKIN-2 RECEPTOR
ELISA TEST PROCEDURE
PRINCIPLE AND PURPOSE OF TEST:
IL-2 receptor alpha chain is one of the key components of the lymphoid cell receptor complex. Interleukin-2(IL-2), plays a pivotal role in initiating and potentiating the immune response. It provides a critical signal necessary for both T Cell proliferation and antibody secretion by B cells. In fact, IL-2 has a wide range of effects upon many lymphoid cells that express
IL-2 receptor including natural killer cells and monocytes. Following stimulation by antigen, all T cells express highaffinity
IL-2 receptors, while those with a T helper phenotype transiently
secrete IL-2. The signal provided by the interaction of IL-2 with its high affinity receptors, composed of a 55-kD "-chain and a 75-kD $-chain, is necessary and sufficient for T cells to undergo G1 progression, S phase transition and subsequent cell division.
IL-2 receptor is the protein that mediates the action of IL-2, and normal T and B cells do not display a significant number of these receptors on their surface. Stimulation of the immune system causes two IL-2R changes:
More molecules of IL-2R " are expressed on the cells plasma membrane and the soluble form of the IL-2 Receptor alpha is released by the activated cells into the surrounding fluid.
The principle of the CELLFREE Human s-IL-2R test kit is an
enzymeimmunoassay (EIA) based on the sandwich principle. It is for determination of soluble Interleukin-2 receptor (IL-2R) levels in human serum, plasma,or cell culture supernatant.
A monoclonal antibody specific for sIL-2R has been coated onto the microtiter plate provided in the kit. Samples and standards are pipetted into the wells of the microtiter plate.
Immediately enzyme conjugated anti-IL-2R monoclonal antibody is added into micotiter wells. The sIL-2R present in the standards or samples binds to the coated antibody while the conjugated antibody binds to a second, distinct epitope on the IL-2R molecule completing the sandwich. After incubation the unbound material present in the sample is removed by washing. Next, a chromogen solution is added to the wells forming a
colored end product that is proportional to the amount of IL-2R present in the samples.
The enzyme reaction is stopped by the addition of Stop solution and the absorbance at 490 nm is measured with a spectrophotometer.
A standard curve is obtained by plotting the optical density (absorbances) versus the corresponding concentrations of defined standards. The human sIL-2R concentration of samples with unknown concentrations, which are run concurrently with the Standards, can be determined from the standard curve.
sIL-2R is normally measurable in plasma, serum, and other body fluids, and the concentration rises in inflammatory and noninflammatory diseases. Any pathological factor which stimulate T-Cells and other cells causes increase in sIL-2R in the circulation.
sIL-2R is a stable marker of immune activation in biologic fluids and cannot be rapidly cleared from the circulation.
Increased concentrations of the sIL-2R are seen in the majority of individuals with human immunodeficiency virus (HIV) infection and other diseases characterized by immune activation (Breast cancer, Multiple Sclerosis, rheumatoid arthritis, etc.). The assay is often described as a useful parameter for evaluating diseases activity, diseases prognosis and evaluation of immune system.