Importance of methodological standardization for the ektacytometric measures of red blood cell deformability in sickle cell anemia

Authors

• N Parrow
• C Renoux
• C Faes
• P Joly
• M Hardeman
• J Tisdale
• M Levine
• N Garnier
• Y Bertrand
• K Kebaili
• D Cuzzubbo
• G Cannas
• C Martin
• V Pialoux
• P Connes

Abstract

Sickle cell anemia (SCA) is characterized by altered red blood cell (RBC) deformability; Variability in the degree of deformability may predict the occurrence of complications. Ektacytometry is the gold standard for measuring RBC deformability. However, analysis of blood from SCA patients requires careful methodological considerations, because rigid cells do not align properly with deformable RBCs in response to shear stress. The percentage of irreversibly sickled cells in a sample can be determined by altering the size of the diffraction pattern using the camera aperture on the commercially available ektacytometer, the LORRCA. The aperture is not accessible on the latest generation of the LORRCA. We investigated whether or not the percentage of irreversibly sickled cells could be estimated using the camera gain to alter the size of the diffraction pattern. We adjusted the camera gain to generate on-screen diffraction pattern sizes of 3.8, 4.5 and 5.4 cm and measured the deformability profile associated with each. Results indicate that RBCs from control subjects adopt an elliptical shape under shear stress, whereas SCA RBCs adopt a diamond shape arising from the superposition of elliptical and round patterns. The round pattern, found only in SCA blood, represents rigid RBCs. Differences in maximal deformability (EImax) and shear stress required to achieve one-half maximum deformation (SS1/2) between the highest and lowest camera gains used reached ~ 10% and ~ 50%, respectively, in samples from subjects with SCA but not controls. These differences correlate with percent sickled cells and hemoglobin S, suggesting this technique has clinical utility.

Scientific Focus Area: Cell Biology

This page was last updated on Friday, March 26, 2021