Abnormal red blood cell morphological changes in thalassaemia associated with iron overload and oxidative stress

Iron overload is a major factor contributing to the overall pathology of thalassaemia, which is primarily mediated by ineffective erythropoiesis and shorter mature red blood cell (RBC) survival. Iron accumulation in RBCs generates reactive oxygen species (ROS) that cause cellular damage such as lipid peroxidation and RBC membrane deformation. Abnormal RBCs in patients with thalassaemia are commonly known as microcytic hypochromic anaemia with poikilocytosis. However, iron and ROS accumulation in RBCs as related to RBC morphological changes in patients with thalassaemia has not been reported.

Twenty-one patients with thalassaemia, including HbH, HbH with Hb Constant Spring and β-thalassaemia/HbE (splenectomy and non-splenectomy) genotypes, and five normal subjects were recruited. RBC morphology was analysed by light and scanning electron microscopy. Systemic and RBC iron status and oxidative stress were examined.

Decreased normocytes were observed in the samples of patients with thalassaemia, with RBC morphological abnormality being related to the type of disease (α-thalassaemia or β-thalassaemia) and splenic status. Target cells and crenated cells were mainly found in splenectomised patients with β-thalassaemia/HbE, while target cells and teardrop cells were found in non-splenectomised patients. Patients with thalassaemia had high levels of serum ferritin, red cell ferritin and ROS in RBCs compared with normal subjects (p<0.05). Negative correlations between the amount of normocytes and serum ferritin (r_s=-0.518, p=0.011), red cell ferritin (r_s=-0.467, p=0.025) or ROS in RBCs (r_s=-0.672, p<0.001) were observed.

Iron overload and its consequent intracellular oxidative stress in RBCs were associated with reduce normocytes in patients with thalassaemia.