CD8A and immunoglobulin G4-related sclerosing disease: In conclusion, iguratimod plus corticosteroid as bridge therapy is effective for the treatment of mild IgG4‐RD; it can improve the clinical symptoms of patients, reduce the serum IgG and IgG4 levels, and can also reduce the peripheral CD3+ CD8+ T cells, and especially plasmablasts and memory B cells.