Reduced antioxidant capacities in platelets from patients with autoimmune thrombocytopenia purpura (ITP)

Abstract

Autoimmune thrombocytopenic purpura (ITP) is characterized by an abnormally low platelet count and bleeding risks. The exact triggering event remains elusive. Oxidative stress may play a role in several autoimmune diseases. A direct link between platelets in ITP and oxidative stress has not yet been addressed. The intracellular platelet antioxidant capacity (AOC) in ITP patients in the active phase (n = 24) and remission (n = 12), and 44 healthy controls were analysed with 2′,7′-dichlorodihydrofluorescein diacetate, and in combination with hydrogen peroxide. Enzyme activities (EA) of serum glutathione peroxidase (GPx), glutathione reductase (GRed) and catalase (CAT) were investigated colourimetrically in patients and controls. The AOC of ITP patients in the active phase was drastically reduced, with significantly high mean fluorescence intensity values. Higher GPx activity was observed in both active phase and remission in comparison to healthy controls (p < 0.001), with greater activity observed in active ITP than remission (p = 0.001). However, GRed EA was not elevated indicating that reduced glutathione (GSH) is not comparably recovered as consumed, leading to a decreased bioavailability of GSH and increased oxidative stress. These results suggest that oxidative stress is implicated in active ITP and may play a crucial role in its pathophysiology.