title: Specific binding of 125I-human interferon-gamma to high affinity receptors on human fibroblasts.
abstract: Highly purified human interferon-gamma (IFN-gamma) was iodinated with 125I-Bolton-Hunter reagent to a specific activity of 34 microCi/micrograms of protein. After iodination, molecular sieve chromatography was used to isolate fractions containing IFN-gamma at approximately 80-90% radioactive purity. This preparation of 125I-IFN-gamma bound specifically to high affinity binding sites on human GM-258 fibroblasts. Scatchard analysis of binding data revealed the presence of 2400 binding sites/cell, each binding with an apparent Kd of 1.5 X 10(-10) M. Binding was competitively inhibited in the presence of unlabeled IFN-gamma and, to a lesser degree, by IFN-beta, but not by IFN-alpha. Neutralizing antibodies specific for IFN-gamma efficiently inhibited the specific binding of 125I-IFN-gamma to cells. We conclude that the specific high affinity binding site is the receptor for IFN-gamma.
mesh_terms: D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007700:Kinetics; D011865:Radioisotope Dilution Technique; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017471:Receptors, Interferon
chemical_list: D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D017471:Receptors, Interferon; D007371:Interferon-gamma