Chronic oxidative stress reduces the respiratory burst response of neutrophils from beta-thalassaemia patients.
Beta-thalassaemia patients are susceptible to infections by mechanisms that are not fully understood. Polymorphonuclear neutrophils (PMN) destroy microbes by producing a burst of reactive oxygen species (ROS) (respiratory burst) in response to bacterial components, as well as to phorbol-myristate-acetate (PMA). In the present study, we compared ROS generation by normal and beta-thalassaemia PMN and assessed their response to PMA. Blood cells were subjected to gelatin separation, staining with dichlorofluorescin-diacetate and flow cytometry. At basal level, the fluorescence (mean fluorescence channel) of normal and thalassaemia PMN were 12.7 +/- 4.5 and 95.6 +/- 19.8 respectively; it changed to 283.4 +/- 72.5 and 39.5 +/- 14.3, respectively, upon PMA stimulation, indicating that thalassaemia PMN have a higher basal ROS but a reduced response to PMA. When normal PMN were treated with the oxidants hydrogen peroxide and butyl-hydroxyperoxide, as well as iron and haemin, which are elevated in thalassaemia, their basal ROS increased 5-22-fold, but the PMA response was abolished. Treating thalassaemic PMN with antioxidants (N-acetyl-L-cysteine or vitamins C and E) reduced their basal ROS but enhanced their PMA response. Our findings indicate that chronically stressed PMN, e.g. in thalassaemia, have reduced capacity to elicit a respiratory burst, which may compromise their antibacterial capacity, and imply prophylactic treatment with antioxidants for recurrent infections.
Amer
Johnny
J
Department of Haematology, Hadassah-Hebrew University Medical Centre, Jerusalem 91120, Israel.
Fibach
Eitan
E
D000975:Antioxidants / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000097:blood; D016897:Respiratory Burst; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D017086:beta-Thalassemia / Q000097:blood*
D000975:Antioxidants; D016877:Oxidants; D017382:Reactive Oxygen Species; D013755:Tetradecanoylphorbol Acetate