The objective of this study was to investigate whether TIGIT expression could detect high IL-21-producing peripheral Tfh populations and their association with disease activity in IgG4-RD.<h4>Methods</h4>TIGIT expression in peripheral CD4+T cell subsets was comprehensively analyzed by multi-color flow cytometry. This evidence concerns the gene IL21 and immunoglobulin G4-related sclerosing disease.