IL6 and immunoglobulin G4-related sclerosing disease: As shown in Fig. 2, serum concentrations of prototypical pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α were comparable among CP and type 1 AIP/IgG4-RD patients except for one type 1 AIP case that exhibited a remarkably high concentration of TNF-α.