The GC payload contributes to the immunosuppressive effect of BDCA2-ADC. (A, B) The expression of NF-κB pathway members (A) and select GC-regulated genes (B) in in vitro-treated pDCs was analysed by RNA-seq. (C) 293T cells were transfected with a GRE-containing luciferase reporter with or without the BDCA2 plasmid. The cells were stimulated with either BIIB059 or BDCA2-ADC. GR activation was measured based on the results of a luciferase assay after 24 h. ADC: antibody–drug conjugate; BDCA2: blood dendritic cell antigen 2; DUSP1: dual specificity protein phosphatase 1; GC: glucocorticoid; GILZ: GC-induced leucine zipper protein; GRE: GC response element; FPKM: fragments per kilobase per million mapped reads; IRAK3: IL-1 receptor associated kinase 3; ISO ADC: human IgG1 Isotype-ADC; NF-κB: nuclear factor κB; NFKBIA–NFKBIE: NF-κB inhibitor α–ε; pDC: plasmacytoid dendritic cell