Laser Diffraction Patterns of Sickle Cells in Fluid Shear Fields
Under the action of fluid shear stresses the normal biconcave red cells deform into ellipsoids and align themselves parallel to the direction of flow. The laser diffraction pattern produced by biconcave red cells in the ektacytometer is circular and is transformed into an ellipse under the action of applied fluid stress. In contrast, red blood cells from sickle cell patients gave a ‘cross’ diffraction pattern under the action of applied stress. This cross diffraction pattern was determined to be due to the different orientations of irreversibly ‘sickled’ cells (ISCs) and discocytes (non-ISCs) in the shear field. The ISCs oriented in a direction perpendicular to the direction of flow and rotated around their own axis. This cross diffraction pattern is unique for sickle cells and distinguishes it from red cells of all the other hemolytic anemias. From the intensity of the signal in the horizontal ellipse the percentage of ISCs in patients’ blood can be quantified.
Key WordsRed cell deformability Sickle cells Laser diffractometry.
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