CD4 and rheumatoid arthritis: We found no significant differences in the percentage of CD25+CD127low Treg cells within CD4+CD45RO+ T cells between PB samples from RA patients and those from healthy controls (each n = 42), even when the groups were age‐matched (mean ± SD age 49 ± 2.4 years in RA patients versus 49 ± 2.5 years in healthy controls [each n = 20]) (Figure 1A).