Description
Introduction: Interleukin 4 (IL-4, B-cell growth factor-1, BSF-1) is a T-cell derived cytokine with a molecular weight of approximately 15 to 19 kD. It plays an important role in the activation of resting B-cells and the subsequent proliferation and differentiation of B-cells. IL-4 is essential for IgE synthesis in vitro and the involvement with allergic diseases has been investigated. Furthermore, IL-4 was found to inhibit the secretion of IL-1B,TNF-a and IL-6 of human monocytes, to down-regulate the surface expression of CD5 on B-cells and to promote the growth of human T-cells. Also anti-inflammatory effects of IL-4 have been reported. Several studies have been conducted to assess the role of IL-4 in several autoimmune diseases. Bioassays for the quantification of IL-4, based on T-cell proliferation have been used for several years. These assays, although sensitive, are time consuming and susceptible to interference by other substances.
Principle of the Assay: The microtiter plate provided in this kit has been pre-coated with an antibody specific to IL-4. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody preparation specific for IL-4 and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB (3,3',5,5' tetramethyl-benzidine) substrate solution is added to each well. Only those wells that contain IL-4, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450 nm +/- 2 nm. The concentration of IL-4 in the samples is then determined by comparing the O.D. of the samples to the standard curve