ERYTHROCYTE-MEMBRANE ALTERATIONS IN THALASSEMIA-INTERMEDIA

The erythrocyte membrane alterations were studied in nineteen beta-tha lassemia intermedia patients. Solubilized erythrocyte membrane protein s were gel-filtered and high-molecular-weight aggregates were isolated and analyzed for denatured hemoglobin derivatives. All the patients p resented increased amounts of membrane-bound heme, hemichromes and imm unoglobulins, together with aggregation and oxidation of band 3. The b asal activity of the erythrocyte pentose-monophosphate-pathway was nor mal, whereas a lower susceptibility to in vitro methylene blue stimula tion was observed. In five randomly-selected patients, whole blood vis cosity resulted approximately normal, while filterability was signific antly lower, suggesting a decrease in red blood cells deformability. A relation between hemichrome-induced band 3 aggregation and theologic modifications of red blood cells was observed. Hemichrome binding to b and 3 seems likely to be an important event leading to membrane damage s and, hence, responsible for erythrocytes removal from blood circulat ion by the phagocytic system. Density gradient separation of erythrocy te subpopulation was performed in a selected case and the same biochem ical, redox status and theologic parameters were determined. The oldes t cells have no detectable hemichromes and their deformability is bett er than that of cells containing a relevant amount of hemichromes. Cop yright (C) 1996 Elsevier Science Ltd.