CD4 and immunoglobulin G4-related sclerosing disease: Yet, although expansion of peripheral blood lymphocyte subsets, such as plasmablasts and CD4+ cytotoxic T lymphocytes, have been described in IgG4-RD patients [33, 34, 40], no decrease of immune cell subsets or immune-deficient state has yet been associated with IgG4-RD, including in patients treated with RTX so far.