Evidence obtained from preclinical and clinical studies from animal models of RA and RA patients demonstrates that CD4+ T cells belonging to the proinflammatory subgroups Th1 and Th17, together with M1 macrophages, contribute to the development and maintenance of RA and counteract the action of Th2 and Th3 anti-inflammatory cells and M2 macrophages [8]. This evidence concerns the gene CD4 and rheumatoid arthritis.