title: Recombinant human immune interferon induces increased IgE receptor expression on the human monocyte cell line U-937.
abstract: Human recombinant gamma interferon (IFN-gamma), which is free from other lymphokines, significantly increased expression of receptors for IgE (Fc epsilon R) on the human monocyte cell line U-937. Fc epsilon R were measured by assaying specific (saturable) binding of 125I-labeled or fluorescein isothiocyanate (FITC)-labeled human IgE (Sha) to U-937 cells. Cell-bound IgE was analyzed by gamma counting and by flow cytometry. IFN-gamma-induced enhancement in IgE binding was a consequence of an increase in the number and density of Fc epsilon R, as cell size did not change significantly after treatment. Scatchard analysis of 125I-IgE binding curves revealed the presence of a homogeneous population of binding sites for IgE in control and in IFN-gamma-treated cells. IFN-gamma treatment did not change the value of the dissociation constant of Fc epsilon R for 125I-IgE. IFN-alpha and IFN-beta had only slight effects on the expression of Fc epsilon R. Dexamethasone (200 nM) diminished the IFN-gamma-induced enhancement in the number of Fc epsilon R by about 50%, the same extent as in control cells. IFN-gamma treatment did not cause a significant alteration in cell number, cell cycle kinetics, or macromolecular synthesis, and enhanced expression of Fc epsilon R was probably not mediated through the cyclic AMP system.
mesh_terms: D002453:Cell Cycle; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D007371:Interferon-gamma / Q000502:physiology*; D007700:Kinetics; D008213:Lymphocyte Activation; D009000:Monocytes / Q000378:metabolism*; D011961:Receptors, Fc / Q000032:analysis / Q000096:biosynthesis* / Q000187:drug effects; D017455:Receptors, IgE
chemical_list: D011961:Receptors, Fc; D017455:Receptors, IgE; D007073:Immunoglobulin E; D003907:Dexamethasone; D007371:Interferon-gamma; D000242:Cyclic AMP