USP18 and infection: Since USP18 is itself an interferon response gene and LCLs are characterised by a strong interferon signature driven by active infection with the Epstein-Barr virus, we characterised the expression of USP18 in naive B-cells as well as B-cells stimulated with interferon-alpha and TLR7/8 agonist R848 for 16, 40 and 64 h.