CCL21 and rheumatoid arthritis: Discrete expression of CXCL13, CXCL12, and CCL21 has been described in salivary glands of patients with SS, RA, multiple sclerosis, primary sclerosing cholangitis, atherosclerosis, inflammatory bowel disease, chronic lung diseases, Helicobacter pylori-induced gastritis, and lymphoma [reviewed in Ref.