human IFN-gamma ELISA kit (96 Wells)

Interferon gamma (IFN-gamma) is a multifunctional protein first observed as an antiviral activity in cultures of Sindbis virus-infected human leukocytes stimulated by PHA (1). Produced by Tlymphocytes and natural killer (NK) cells, IFN-gamma is now known to be both an inhibitor of viral replication and a regulator of numerous immunological functions. Human IFN-gamma is reported to be active only on human and non-human primate cells (5). The biochemistry and biological activities of the interferons have been extensively reviewed (2-9).
Human IFN-gamma is a 143 amino acid residue, 20 or 25 kDa glycoprotein that demonstrates little sequence homology to IFN-gamma or -gamma (10-13). Naturally occurring IFN-gamma is found as either of two molecular weight species, differing in degree of glycosylation. Human IFN-gamma apparently exists as a head-to-tail dimer in solution with the C-terminus of one monomer aligned with the N-terminus of the other monomer (14,15) A receptor for IFN-gamma has been identified and its gene localized to chromosome 6 (16,17) Apparently the product of a single gene, the receptor is a single chain 90 kDa glycoprotein that shows a high degree of species-specific binding of IFN-gamma (18-21).
Functionally, IFN-gamma produces a variety of effects. Produced by CD8+, NK, gd, and TH1 T helper cells, IFN-gamma has documented antiviral, antiprotozoal and immunomodulatory effects on cell proliferation and apoptosis, as well as the stimulation and repression of a variety of genes (9, 22-25) he antiprotozoal activity of IFN-gamma against Toxoplasma and Chlamydia is believed to result from indoleamine 2,3-dioxygenase activity, an enzyme induced by IFN-gamma (26).The immunomodulatory effects of IFN-gamma are extensive and diverse. In monocyte/macrophages, the activities of IFN-gamma include: increasing the expression of class I and II MHC antigens; increasing the production of IL-1, platelet-activating factor, H2O2, and pterin; protection of monocytes against LAK cell-mediated lysis; downregulation of IL-8 mRNA expression that is upregulated by IL-2; and, with lipopolysaccharide, induction of NO production.Finally, IFN-gamma has been shown to upregulate ICAM-1, but not E-Selectin or VCAM-1, expression on endothelial cells.

For the quantitative determination of human gamma-interferon (IFN-gamma) concentrations in cell culture supernates, serum, and plasma.

Principle of the assay: This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for IFN-gamma has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any IFN-gamma present is bound by the immobilized antibody. Following incubation unbound samples are removed during a wash step, and then a detection antibody specific for IFN-gamma is added to the wells and binds to the combination of capture antibody- IFN-gamma in sample. Following a wash to remove any unbound combination, and enzyme conjugate is added to the wells. Following incubation and wash steps a substrate is added. A colored product is formed in proportion to the amount of IFN-gamma present in the sample. The reaction is terminated by addition of acid and absorbance is measured at 450nm. A standard curve is prepared from seven IFN-gamma standard dilutions and IFN-gamma sample concentration determined.