FOXP3 and rheumatoid arthritis: Furthermore, a lot of research estimated the number of CD4+CD25+ and FOXP3+ T cells in peripheral blood mononuclear cells of patients diagnosed with MS, T1D, and RA, and found no distinctions in the frequency of these cells towards with reference group (Brusko et al. 2005; Cao et al. 2003; Feger et al. 2007; Haas et al. 2005).