IL-4+ Tfh cells were reported to be significantly increased in secondary lymphoid organs and lesion tissues in IgG4-RD [7], and these IL-4+ Tfh cells express BATF, rather than GATA-3, which was identified as a master transcriptional factor of circulating Tfh2 [10]. Here, IL4 is linked to immunoglobulin G4-related sclerosing disease.