Rheological properties of erythrocytes in heterozygous and homozygous beta thalassaemia.

The rheological properties of erythrocytes were studied in 12 heterozygous and nine homozygous beta thalassaemia patients, using filtration of erythrocytes through polycarbonate sieves with a pore diameter of 5 micron and viscosity measurements of erythrocyte and ghost suspensions. Erythrocyte deformability of all patients was decreased. In the heterozygous patients moderately diminished flexibility of cells was due to microcytosis of erythrocytes. Rigidity of erythrocytes in homozygous patients was due to altered cell shape, diminished fluidity of haemoglobin, and in splenectomized patients to the presence of inclusion bodies. Membrane flexibility of erythrocytes remained unaltered. We suggest that the decreased fluidity of haemoglobin as well as the presence of inclusion bodies result from the excess of alpha chains in erythrocytes of homozygous patients. The haemoglobin fluidity of erythrocytes of one patient with thalassaemia intermedia was unchanged. The flexibility of these cells was only moderately altered. In four patients who needed transfusions every 1--4 weeks deformability of transfused erythrocytes was likewise decreased when compared to controls. Erythrocyte suspensions obtained from the splenic artery and vein during splenectomy showed decreased flexibility of transfused cells after their passage through the spleen.