Description
Principle of the assay: The microtiter plate provided in this kit has been pre-coated with an antibody specific to IFN-gamma. Standards or samples are then added to the appropriate microtiter plate wells with a HRP-conjugated antibody preparation specific for IFN-gamma and incubated. Then substrate solution is added to each well. Only those wells that contain IFN-gamma and HRP-conjugated antibody 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 IFN-gamma in the samples is then determined by comparing the O.D. of the samples to the standard curve.
Background: Interferon gamma (IFNgamma) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheelock as a product of human leukocytes stimulated with phytohemagglutinin, and by others as a product of antigen-stimulated lymphocytes or tuberculin-sensitized mouse peritoneal lymphocytes challenged with PPD; the resulting supernatants were shown to inhibit growth of vesicular stomatitis virus. Those reports also contained the basic observation underlying the now widely employed interferon gamma release assay used to test for tuberculosis. In humans, the IFNgamma protein is encoded by the IFNG gene