CD4 and immunoglobulin G4-related sclerosing disease: Mattoo et al. demonstrated that CD4+ CTL cells which also expressed signalling lymphocytic activation molecule F7 (SLAMF7) were expanded in patients with IgG4-RD, and these cells expressed granzyme B, perforin, IL-1β, TGF-β and IFN-γ, which may be important mediators of tissue damage [43].