The receptor for interferon-gamma on human peripheral blood monocytes consists of multiple distinct subunits.
The interaction of interferon-gamma (IFN gamma) (a product of activated T lymphocytes) and monocytes is essential for immune responsiveness, host defense, and chronic inflammation. In this report we define the IFN gamma receptor (IFN gamma R) on human monocytes as a receptor complex consisting of at least three subunits. Solubilization and immunoprecipitation of [35S]methionine- and [35S]cysteine-labeled monocytes were optimized by controlling the detergent concentration during solubilization and washing of the immunoprecipitates. This enabled subunits to be coimmunoprecipitated by several different anti-IFN gamma R antibodies raised against the 90-kDa cloned binding protein. Immunoprecipitation under stringent (1% sodium dodecyl sulfate) conditions resulted in the visualization of only the 80-90-kDa binding protein. Under less stringent conditions at least two coimmunoprecipitated subunits (molecular mass of 200 and 38 kDa) were consistently associated with the 80-kDa (90-92 kDa reduced) binding protein. The 38-kDa subunit was shown to be distinct from the 80-kDa subunit by proteolytic fragment analysis. Cross-linking of 125I-rIFN gamma to monocytes yielded receptor-IFN gamma complexes consistent with the existence of multiple subunits.
Finbloom
D S
DS
Division of Cytokine Biology, Food and Drug Administration, Bethesda, Maryland 20892.
Wahl
L M
LM
Winestock
K D
KD
D000911:Antibodies, Monoclonal; D003545:Cysteine / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D046911:Macromolecular Substances; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology*; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D017471:Receptors, Interferon; D013462:Sulfur Radioisotopes
D000911:Antibodies, Monoclonal; D046911:Macromolecular Substances; D011971:Receptors, Immunologic; D017471:Receptors, Interferon; D013462:Sulfur Radioisotopes; D007371:Interferon-gamma; D008715:Methionine; D003545:Cysteine