CD4 and HIV infectious disease: The importance of Cys2 and GSH in relation to HIV infection is underscored by the fact that the decrease in CD4+ T cell numbers in the late asymptomatic stage of HIV seemed to coincide with a decrease in plasma Cys2 [4], and likewise the concentrations of glutathione reductase was found to be lower in patients with symptomatic HIV than in asymptomatic HIV patients [54].