INTENDED USE

This Human Interleukin-2 soluble receptor alpha ELISA Kit is to be used for the in vitro quantitative determination of human interleukin-2 soluble receptor alpha (IL-2 sRα) concentrations in serum, plasma, cell culture supernatant, and other biological fluids. This kit is intended FOR LABORATORY RESEARCH USE ONLY and is not to be used in diagnostic or therapeutic procedures.

INTRODUCTION

The biological function of IL-2 is obtained by binding to the specific interleukin-2 receptor (IL-2R). The IL-2R consists of three non-covalently linked chains, all of which are type I transmembrane proteins and include the α chain (IL-2Rα, p55), βchain (IL-2Rβ, p75), and g chain (IL-2Rγ, p65). The α chain is cleaved from the cell surface via nonspecific proteolysis.

IL-2Rα and IL-2Rβγdimers bind to different residues on the IL-2 protein. The IL-2Rα complex displays low affinity and the IL-2Rαβ complex displays intermediate affinity for IL-2 binding. Both IL-2Rα and IL-2Rαβcomplexes are unable to transduce a signal. The IL-2Rβγcomplex has intermediate affinity for IL-2 binding and can transduce a signal with a relatively high concentration of IL-2. The IL-2Rαβγ trimer is the high-affinity receptor for IL-2 and can transduce a signal successfully.

Many cells are capable of expressing IL-2Rα including the antigen-activated T cells and B cells, and approximately 10% of natural killer (NK) cells, leukemia and lymphoma cells. When produced by activated T cells, the α chain is? 10-20 folds in excess of the βand γchain. A soluble IL-2Rα can be detected in tissue culture media of IL-2R+ cells and in the serum of experimental animals and humans undergoing an immune response.

The major biological activities of IL-2R include promoting the proliferative expansion of T cells and NK cells upon activation, promoting the persistence of antigen-selected memory T cells, and promoting homeostasis of the immune system after it has successfully responded to an antigen. However, the biological activity of soluble IL-2Rα is unclear. It has been reported that elevated IL-2 sRα level is accompanied by increased T and B cell activation and immune system activation as observed in rheumatoid arthritis, systemic lupus erythematosis (SLE), some leukemias and lymphomas. Because of its low affinity, IL-2 sRα would be expected to be an inhibitor of IL-2.

This IL-2 sRα ELISA is a ready-to-use 4.5-hour solid phase immunoassay capable of measuring IL-2 sRα levels in serum, plasma, cell culture supernatant, and other biological fluids in the range of 0 to 2000 pg/mL. This assay has shown no cross-reactivity with other cytokines tested, and is expected to be used effectively for further investigations into the relationship between IL-2 sRα and the various conditions mentioned.