CD4 and synovial sarcoma: The expression of autoantigens, including Ro60/Sjögren Syndrome type A antigen (SSA), La/Sjögren Syndrome type B antigen (SSB), α-fodrin, β-fodrin, and the M3 acetylcholine receptor, is thought to be an important trigger for the inflammatory epitheliopathy in SS by mechanism involving clustered differentiation (CD4)+ T cell activation [20,21].