Our studies revealed further that peripheral CD4+ T cells from lupus patients, but not from patients with other autoimmune diseases (such as rheumatoid arthritis, primary Sjögren's syndrome, autoimmune deafness, polymyositis, primary billiary cirrhosis and autoimmune hepatitis) or infectious diseases, very specifically recognized the 131–151 and P140 peptides, and that phosphorylation of Ser140 prevented ex vivo proliferation of lupus patients' CD4+ T cells but not secretion of high levels of regulatory cytokines [11]. Here, CD4 is linked to rheumatoid arthritis.