IgG4-RD is a chronic fibro inflammatory disease characterized by a significant elevation of serum IgG4 concentration and marked infiltration of IgG4-positive plasma cells in the affected organs. A dense lymphoplasmacytic infiltrate and the formation of ectopic lymphoid structures are characteristic histopathological findings in an IgG4-RD lesions. These findings strongly suggest the preferential involvement of T and B lymphocytes in the development of this disease. We want to sum up the last evidences regarding the IgG4-RD with a focus on the role of the involvement of CD4+T-cell subsets and B lymphocytes.