Potential pathways in the pathogenesis of IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic disease characterized by elevated serum IgG4 and a marked infiltration of IgG4-positive plasma cells into affected organs. Regarding the immunological aspects of this disease, it is well known that IgG4 is induced by T helper type 2 (Th2) cytokines such as interleukin (IL)-4 and IL-13. Thus, IgG4-RD is considered to be a Th2-predominant disease. In addition, innate immune cells have recently received increasing attention with regards to the initiation of IgG4-RD. Exploring the mechanism of innate and acquired immunity in IgG4-RD is a highly promising field of investigation. In this chapter, we focus on the selective localization and functions of individual Th subsets and innate immune cells to clarify the contribution of these cells to the pathogenesis of IgG4-RD.