Human IL-2R ELISA Kit (48-well)

• Aluminium pouches with a Microwell Plate coated with monoclonal antibody to human IL-2 sRa(8x6)
• 2 vials human IL-2 sRaStandard lyophilized, 10 ng/ml upon reconstitution
• 2 vials concentrated Biotin-Conjugate anti-human IL-2 sRamonoclonal antibody
• 2 vials Streptavidin-HRP solution
• 1 bottle Standard /sample Diluent
• 1 bottle Biotin-Conjugate antibody Diluent
• 1 bottle Streptavidin-HRP Diluent
• 1 bottle Wash Buffer Concentrate 20x (PBS with 1% Tween-20)
• 1 vial Substrate Solution
• 1 vial Stop Solution
• 3 pieces Adhesive Films
• package insert

The biological activities of IL-2 are mediated by its binding to a multi-molecular cellular receptor complex. For several years the receptor was thought to consist of two glycoprotein chains, an alpha chain (IL-2 R.) and a beta chain (IL-2 R.) , which acted together to form a high affinity receptor that transduced the IL-2 signal. IL-2 R. (also known as Tac antigen and as CD25) is a 55 kDa transmembrane glycoprotein composed of 351 amino acids with only 13 located on the cytoplasmic side of the membrane . The second chain of the complex was cloned in 1989 , and is a transmembrane glycoprotein of 575 amino acids (75 kDa), 286 of which are located cytoplasmically and clearly participate in signal transduction . Eventually it was discovered that a third chain, IL-2 R.,was necessary for high affinity binding, ligand internalization and signalling. Constitutively expressed on many lymphoid cells, it had been overlooked partly because it has no affinity for IL-2 except when IL-2 R. is present . When cloned, the gene was found to code for a 64 kDa transmembrane protein of 347 amino acids, 84 of which are cytoplasmic . Both IL-2 R. and IL-2 R. are members of the hematopoietin receptor superfamily, whereas IL-2 R. is related only to the IL-15 R .chain .

A model of the IL-2 receptor complex (3, 9, 16 - 21) would describe the high affinity receptor as an ... trimer, in which all three chains are in contact with the ligand. Alone, IL-2 R. binds IL-2 with low affinity, but is unable to transduce a signal. The .. combination will bind IL-2 with intermediate affinity, but still will not transduce a signal. A .. complex has intermediate affinity and is capable of signalling if the IL-2 concentration is relatively high. Regardless of many subtleties that determine the affinity of the ligand for the extracellular portions of the receptor components , signalling will ensue if the .and .cytoplasmic domains are brought into close proximity .

A soluble form of IL-2 R. appears in serum, concomitant with its increased expression on cells . There are reports of a soluble form of IL-2 R. as well . The function of the soluble IL-2 R. is unclear, since it would be expected to be a poor inhibitor of IL-2 because of its low binding affinity. In any case, increased levels of the soluble IL-2 R. in biological fluids reportedly correlate with increased T and B cell activation and immune system activation. Results of a number of studies suggest a correlation of levels of IL-2 sR. in serum with the onset of rejection episodes in allograft recipients , with activity of autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosis (SLE) and with the course of some leukemias and lymphomas .