Immunoglobulin G4-Related Disease

ABSTRACT

Immunoglobulin G4-related disease (IgG4-RD) is an emerging immune-mediated fibro-inflammatory disorder which can involve any organ. The main characteristics of IgG4-RD are increased serum IgG4 concentration, abundant IgG4+ plasma cells in affected tissues, and painless swollen organs often without general symptoms. Typical pathology features of IgG4-RD are lymphoplasmacytic infiltration, dense storiform fibrosis, and obliterative pheblitis. The pathogenesis of IgG4-RD remains elusive, but involvement of excess production of type 2 T helper cells, regulatory T-cell cytokines, and B-cell activating factor in the development of IgG4-RD has been suggested. Diagnosis of IgG4-RD can be made on the basis of serological, imaging, particularly histopathological findings. Glucocorticoid is the first-line therapy for patients with multiple organ dysfunction and clinical symptoms. Drugs such as azathioprine, mycophenolate mofetil, methotrexate, and cyclophosphamide can be used as steroid-sparing agents. Rituximab is reported to be an effective therapy for treatment of IgG4-RD, even without concomitant glucocorticoid therapy. This review summarizes current concepts on pathophysiology, clinical manifestations, and treatment of IgG4-RD.