Frequencies of CD4+CD25+CD127low Treg cells 34 in the PB from patients with RA were determined within the CD3+CD4+CD45RO+ (memory) T cell compartment, since CD4+CD25high Treg cells are predominantly memory cells 35 and because T cells in the SF are of the CD45RO+ memory phenotype 36. The gene discussed is CD4; the disease is rheumatoid arthritis.