Alterations and pathology of thalassemic red cells: comparison between alpha- and beta-thalassemia.

ABSTRACT

Two main types of thalassemia have been categorized according to defective production of the globin gene ie alpha-thalassemia and beta-thalassemia. We report different red cell abnormalities between these two types. The study included 139 thalassemic patients including 91 patients with hemoglobin (Hb) H disease (52 cases with the classical genotype and 39 cases with Hb Constant Spring) and 48 were beta-thalassemia/Hb E disease. The deformability index of thalassemic red cells measured by laser diffractometer was significantly lower than that of normal red cells. Increased susceptibility of the thalassemic red cells to monocyte phagocytosis was markedly noted. Few sialic acid molecules were scattered on red cell surface of thalassemic red cells. Reticulocytes with delayed maturation stage were also observed in thalassemia indicating enhanced release from the bone marrow. The alpha-thalassemic red cells had relatively better deformability, increased susceptibility to phagocytosis, reduced sialic acid content and greater degree irregular distribution of sialic acid on red cell surface as compared to beta-thalassemic red cells. The alpha-type with hemoglobin Constant Spring (Hb CS) had increased percentage of reticulocyte and young reticulocyte (high fluorescent intensity) as compared to beta-thalassemic red cells. The different abnormalities between alpha- and beta-thalassemic red cells may lead to different mechanism of red cell destruction and different severity of the disease.