TNF and rheumatoid arthritis: Recently, Ho and others found that mice that were immunized with citrullinated fibrinogen developed arthritis and fibrinogen-reactive T cells which produce the proinflammatory cytokines IL-6, IL-17, TNF-alpha, and IFN-gamma and that these mice possess rheumatoid factor (RF), circulating immune complexes and anti-CCP antibodies, all of which are characteristics of human RA [11].