IFNG and immunoglobulin G4-related sclerosing disease: CD4+GZMA+IFN-γ+ CTLs were the most abundant infiltrating T lymphocytes in the IgG4-RD affected tissues, which could synthesize and secrete profibrotic cytokines of IL-1β, TGF-β1 and IFN-γ, as well as release cell-lysing substances such as perforin, granzyme A, and granzyme B (17, 18, 22).