Among other findings, active involvement of Th2- (IL-4, IL-5, and IL-21), T follicular helper cell (Tfh)—(BCL-6 and CXCR5) and Treg-related transcripts (IL-10, FOXP3, CCL18, and TGF-β1) in patients with IgG4-RD were observed. Here, IL4 is linked to immunoglobulin G4-related sclerosing disease.