The oxidation of serum sulph-hydryl groups by hydrogen peroxide secreted by stimulated phagocytic cells in rheumatoid arthritis

Abstract

Levels of free sulph-hydryl (SH) groups are depressed in the sera of patients with rheumatoid arthritis, especially during active disease. However, the mechanism underlying this effect is not known. We have investigated several oxidative species generated during the inflammatory process for their ability to react with serum SH in vitro. Our results show that serum oxidase enzymes (e.g. caeruloplasmin) do not have this activity but that "active oxygen species" generated either by an enzymatic reaction (xanthine plus xanthine oxidase) or by neutrophils stimulated with heat-aggregated IgG cause rapid oxidation of serum SH groups. The use of selective inhibitors of active oxygen species has demonstrated that this reaction is mediated by hydrogen peroxide. This compound is secreted in considerable amounts by activated phagocytic cells, especially neutrophils. Thus, serum SH levels may reflect phagocytic activity in patients with rheumatoid arthritis. We suggest that serum SH groups act as important extracellular scavengers of peroxides and so help to protect cells from damage by these molecules.

Oxidative Stress and Antioxidant Defenses in Plasma of Patients with Behcet's Disease.

“…It is speculated that plasma SH groups act as an important extracellular scavenger of peroxides and are also helpful in protecting the surrounding tissues (Hall et al 1984). Critical SH groups on cell membranes protect proteins against oxidative damage by MPO-derived HOCI (Weiss 1989), while they are consumed.…”

“…Critical SH groups on cell membranes protect proteins against oxidative damage by MPO-derived HOCI (Weiss 1989), while they are consumed. The reduced plasma SH levels have also been attributed to the actions of H2O2 (Hall et al 1984), and transition metal ions (Halliwell and Gutteridge 1990b) promote oxidation of SH groups; further Op is a specific oxidase for SH containing small molecules (Rae et al 1986). In the present study, decreased plasma SH levels were observed in BD patients; and there was a positive correlation between SH and TF levels.…”

Intracellular and extracellular sulphydryl levels in rheumatoid arthritis.

“…It has been reported that the number of free SH groups in the sera of rheumatoid arthritis (RA) patients is depressed.1 2 This depression is associated with the activity of the disease.2 Hall et al 3 have shown in vitro that H202 formed during phagocytosis by granulocytes diminishes the amount of free SH groups. These authors propose that serum SH groups act as important extracellular scavengers of peroxides and are therefore helpful in protecting the surrounding tissues.…”

An investigation of thiol/disulfide homeostasis in patients with Behçet’s disease

“…If there is an imbalance, it can result in the formation of reactive oxygen radicals leading to endothelial dysfunction and apoptosis [30,31]. It has been observed that plasma SH groups act as an important extracellular scavenger of peroxides and are also helpful in protecting the surrounding tissues [32]. Critical SH groups on cell membranes protect proteins against oxidative damage by MPO-derived HOCI, while they are consumed [33].…”