CD4 and rheumatoid arthritis: Romão et al. (74) also found that inactive patients with RA and HCs have similar frequencies of circulating Tfr cells, which is not in line with Liu et al. In addition, the percentage of circulating Tfr cells in CD4+ T cells was significantly reduced in an methotrexate (MTX) treated group compared to a non-treated group, suggesting that therapeutic schedule affects the frequency of Tfr cells.