Cytometric bead assay
The supernatants were collected from the co-cultures at 96 h. IFN-γ levels were measured by a flow cytometry-based bead assay (LEGENDPlex™ Human IFN-γ, BioLegend). MFI values of the samples and the standards were used for calculating the concentration of IFN-γ (LEGENDplex™ Data Analysis Software, BioLegend) as instructed by the manufacturer.