This disulphide bridge has been described to be selectively reduced by Trx1.13 To examine whether reduction of this disulphide bridge may be responsible for higher CD4 downmodulation in healthy subjects compared with RA patients, we further examined the role of Trx1 on Tregalizumab binding to CD4 and the role of Trx1 in RA in general. The gene discussed is CD4; the disease is rheumatoid arthritis.