The viscosity of red blood cell membranes in patients with beta-thalassaemia.

Abstract

The purpose of this work was to study the viscoelastic behaviour of the red blood cell membrane (RBCM) in cells from patients with beta-thalassaemia and to investigate whether the precipitated haemoglobin, which is one of the main features of thalassaemic syndromes, influences the membrane viscosity. RBCM viscosities were determined using the micropipet aspiration method. A negative pressure of about 50 Pa was applied in steps at the membrane surface so as to cause partial aspiration of the cell and the entry process was analyzed automatically by a TV-line analyzer. This analysis enabled estimation of the characteristic times (tau 1, tau 2) and corresponding values of the viscosity (eta 1, eta 2). Results were as follows: eta 1 = (1.87 +/- 0.55) microNs/m and eta 2 = (51.42 +/- 20) microNs/m for erythrocytes from normal donors; eta 1 = (3.97 +/- 0.98) microNs/m and eta 2 = (110.40 +/- 35) microNs/m for erythrocytes from patients. Inclusions (Heinz Bodies) were produced artificially in normal cells and the characteristic times (tau 1, tau 2) and corresponding viscosities (eta 1, eta 2) derived in the same manner. For three types of RBC containing increasing numbers of inclusions, the values were: eta 1 = (3.26 +/- 1.70) microNs/m and eta 2 = (77.33 +/- 46.96) microNs/m; eta 1 = (4.21 +/- 1.49) microNs/m and eta 2 = (129.60 +/- 47.90) microNs/m; eta 1 = (7.93 +/- 2.62) microNs/m and eta 2 = (206.60 +/- 93.19) microNs/m. It is concluded that the association of inclusion bodies with the membrane, either in disease or through artificial production, increases the membrane viscosity.