PF791 IMPAIRMENT OF GLUTATHIONE SYSTEM AND LIPID PEROXIDATION IN PATIENTS WITH HB H DISEASE

Background: Hb H disease, a distinct clinically form of thalassemia intermedia / Non‐Transfusion‐Dependent Thalassemia, is mainly the result of inactivation of 3 α‐globin genes by deletional or non‐deletional mutations. Patients with Hb H disease produce abnormal hemoglobin H composed of β 4 ‐chains tetramers and they have moderate to severe hemolytic anemia, a variable degree of ineffective erythropoiesis and splenomegaly. Hb H is functionally characterized by high oxygen affinity, lack of subunit interaction, marked degree of instability and autoxidation. These result in the formation of insoluble particles within the RBCs which cause local oxidative damage, membrane dysfunction and shortened red cell survival. In this context we aimed to evaluate the RBCs’ glutathione system and membrane lipid peroxidation along with antioxidant defense in patients with Hb H disease Aims: To evaluate the changes in oxidant/antioxidant equilibrium in Patients with Hb H disease. Methods: Twenty‐seven treatment‐ naïve patients with Hb H disease were included in the study, while 15 apparently healthy individuals served as controls. Along with hematologic and blood chemistry parameters, specific antioxidants (vitamins A, E and C) and catabolic products were measured as follows: red cell total glutathione (GSH t ), oxidized/reduced glutathione (GSSG and GSH r respectively) levels by RP‐HPLC with fluorimetric detection (excitation 385 nm and emission 515 nm); malonyldialdehyde (MDA) levels by RP‐HPLC with fluorimetric detection (excitation 532 nm and emission 550 nm); vitamins A and E levels by RP‐HPLC with UV detection at 295 nm, while vitamin C levels were measured by RP‐HPLC with UV detection at 254 nm. Results: Total glutathione as well as GSSG and GSH r levels were significantly lower (by 25%, 45% and 17%, respectively) in patients with Hb H disease compared to controls ( p  < 0.001, p  < 0.001 and p = 0.02, respectively); MDA levels were significantly increased (by 67%) in patients with Hb H disease compared to controls ( p  < 0.001); no significant differences were found in vitamin A and C levels between patients with Hb H disease and controls (p>0.341 and p>0.420, respectively), while vitamin E levels were significantly reduced (by 50%) in patients with Hb H disease compared to controls ( p  < 0.001). Summary/Conclusion: These results demonstrate two important issues. Firstly, the partial deficiency of red cell glutathione system points to increased oxidative status, due to Hb H instability, denaturation and precipitation in the RBCs of the patients. The same phenomenon is observed in patients with Sickle Cell Disease and might probably be due to altered concentrations of the metabolites serving as substrates in the glutathione system (e.g. L‐glutamine). Secondly, the overall membranes’ lipid peroxidation and manonyldialdehyde formation are detrimental to cellular integrity and function, which are further deteriorated by the partial deficiency of tocopherols. These observations support potential clinical benefit of the administration of glutathione system precursors and/or vitamin E in patients with Hb H disease.