The overexpression of IL10, TGFβ, and activation-induced cytidine deaminase (AID) has been reported in the labial salivary glands (LSGs) of IgG4-RD patients in comparison to SS patients, suggesting that Treg cytokines (IL10 and TGFβ) combined with AID, an IgG4-unrelated molecule in IgG4-RD (MD) patients, contributes to IgG4-specific class switch recombination and fibrosis [87]. This evidence concerns the gene TGFB1 and immunoglobulin G4-related sclerosing disease.