TNFSF13B and synovial sarcoma: The relevance of activated type I IFN system in SS is further strengthened by the depiction of several INFα-producing cells in salivary gland of SS patients leading to subsequent apoptosis of salivary epithelial cells, exposure of endogenous autoantigens to the immune system, upregulation of BAFF expression, increased B cell survival and differentiation, and ultimately autoantibody production and immunocomplex formation (23).