For instance IL-4, the signature cytokine of CD4+ Th2 cells, is known to reduce the production of Th1 cytokines by RA synovium [23] - and IL-4 has been used in vivo as a treatment for a number of experimental autoimmune diseases in animals, including collagen-induced arthritis (CIA) [24]. The gene discussed is IL4; the disease is rheumatoid arthritis.