Fig. 2.

Schematic model of CD4+ cytotoxic T lymphocytes (CTLs) in IgG4-RD pathogenesis. Clonal expansion of CD4+ CTLs and their infiltration into tissue sites may be the cause of this disease state. Reactivation of these CD4+ CTL cells may require antigen presentation by plasmablasts or other activated B cells in tissue sites. Activated CD4+ CTLs presumably mediate fibrosis and inflammation as a result of cytokine secretion or possibly the induction of cell death. The mechanisms by which CD4+ CTLs may cause disease remain speculative. Reproduced from Maehara et al. [13] with permission.