CD4 and rheumatoid arthritis: CD4+ T cells in both SE+ RA patients and HLA-DR4+ healthy controls have reduced T-cell-receptor excision circles, overall telomere shortening, and reduced replicative capacity, which together imply an HLA-DR SE-associated reduction in T-cell input to the peripheral repertoire, an increased proliferative drive for naïve T cells towards peripheral self-antigens and a limited diversity of the TCR repertoire [45-47].