Santer DM Minty GES Mohamed A Baldwin L Bhat R Joyce M Egli A Tyrrell DLJ Houghton M 2017 Type III interferons (IFN-lambdas) are important antiviral cytokines that also modulate immune responses acting through a unique IFN-λR1/IL-10R2 heterodimeric receptor. Conflicting data has been reported for which cells express the IFN-λR1 subunit and directly respond to IFN-λs. In this study we developed a novel method to measure IFN-λ3 binding to IFN-λR1/IL-10R2 on the surface of cells and relate this to a functional readout of interferon stimulated gene (ISG) activity in various cell lines. We show that Huh7.5 hepatoma cells bind IFN-λ3 at the highest levels with the lowest Kd(app), translating to the highest induction of various ISGs. Raji and Jurkat cell lines, representing B and T cells, respectively, moderately bind IFN-λ3 and have lower ISG responses. U937 cells, representing monocytes, did not bind IFN-λ3 well and therefore, did not have any ISG induction. Importantly, knockdown of IFNLR1 in Huh7.5 cells decreased our binding signal proportionally and reduced ISG induction by up to 93%. IFN-λ3 responsiveness increased over time with maximal ISG responses seen at 24h for all but one gene. These data confirm our new IFN-λ3 binding assay can be used to quantify IFN-λ receptor surface expression on a variety of cell types and reflects IFN-λ3 responsiveness. https://sonar.ch/global/documents/232363 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jim.2017.03.001 info:eu-repo/semantics/altIdentifier/pmid/28274837 Journal of immunological methods. - 2017 Binding assay Flow cytometry Interferon-lambda Interferon-lambda receptor Interferon-stimulated genes Binding Sites Cell Line, Tumor Flow Cytometry Humans Interferons Interleukins Receptors, Interferon A novel method for detection of IFN-lambda 3 binding to cells for quantifying IFN-lambda receptor expression. http://purl.org/coar/resource_type/c_6501