CD4 and immunoglobulin G4-related sclerosing disease: Such abnormalities of specific lymphocyte subsets are present in the blood of patients with IgG4-RD, including CD4+ cytotoxic T lymphocytes (CTL), follicular helper T (Tfh) cell, CD19+CD24−CD38hi plasmablasts/plasma cells, and so on [32, 40–44], and the role of Eosinophil in IgG4-RD has been reported in previous studies [15, 16, 45, 46].