In addition, the blood concentration of the CD4+SLAMF7+ CTLs slowly declines following B cell depletion in IgG4-RD patients, suggesting a direct link between B cells lineage and CD4+SLAMF7+ CTLs in the pathogenetic mechanisms of IgG4-RD. Here, SLAMF7 is linked to immunoglobulin G4-related sclerosing disease.