Description
Principle of the assay: This assay employs a two-site sandwich ELISA to quantitative IL-35 in Human serum, plasma, tissue homogenates, cell lysates. An antibody specific for IL-35 has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any IL-35 present is bound by the immobilized antibody. After removing any unbound substances, a biotin - conjugated antibody specific for IL-35 is added to the wells. After washing, Streptavidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of IL-35 bound in the initial step. The color development is stopped and the intensity of the color is measured.
Background: Interleukin 35 (IL-35) is an IL-12 family cytokine produced by regulatory, but not effector, T-cells and plays a role in immune suppression. It is a dimeric protein composed of IL-12alpha and IL-27beta chains, which are encoded by two separate genes called IL12A and EBI3, respectively. Secreted by regulatory T-cells (Tregs), IL-35 suppresses inflammatory responses of immune cells. IL-35 is not constitutively expressed in tissues, but the gene encoding IL-35 is transcribed by vascular endothelial cells, smooth muscle cells and monocytes after activation with proinflammatory stimuli. Studies in mice show the absence of either IL-35 chain from regulatory Tregs reduces the cells' ability to suppress inflammation; this has been observed during cell culture experiments and using an experimental model for inflammatory bowel disease. To produce its suppressive effects, IL-35 has selective activities on different T-cell subsets; it induces proliferation of Treg cell populations but reduces activity ofTh17 cell populations