Interactions of GSH and cysteine pools in human plasma. To determine the interactions of the GSH/GSSG and Cys/CySS pools, thiol and disulfide forms were measured in plasma from 24 healthy individuals aged 25-35 (26). In this study, GSH concentration correlated with Cys concentration, but no correlations were observed between GSSG and CySS or between the reduced and oxidized components. The lack of equilibration of these values supports the interpretation that plasma GSH and Cys redox values are dynamic indicators of the systemic balance between oxidative and antioxidant processes (26).