title: Deformability analysis of sickle blood using ektacytometry.
abstract: Sickle cell disease (SCD) is characterized by decreased erythrocyte deformability, microvessel occlusion and severe painful infarctions of different organs. Ektacytometry of SCD red blood cells (RBC) is made difficult by the presence of rigid, poorly-deformable irreversibly sickled cells (ISC) that do not align with the fluid shear field and distort the elliptical diffraction pattern seen with normal RBC. In operation, the computer software fits an outline to the diffraction pattern, then reports an elongation index (EI) at each shear stress based on the length and width of the fitted ellipse: EI=(length-width)/(length+width). Using a commercial ektacytometer (LORCA, Mechatronics Instruments, The Netherlands) we have approached the problem of ellipse fitting in two ways: (1) altering the height of the diffraction image on a computer monitor using an aperture within the camera lens; (2) altering the light intensity level (gray level) used by the software to fit the image to an elliptical shape. Neither of these methods affected deformability results (elongation index-shear stress relations) for normal RBC but did markedly affect results for SCD erythrocytes: (1) decreasing image height by 15% and 30% increased EI at moderate to high stresses; (2) progressively increasing the light level increased EI over a wide range of stresses. Fitting data obtained at different image heights using the Lineweaver-Burke routine yielded percentage ISC results in good agreement with microscopic cell counting. We suggest that these two relatively simple approaches allow minimizing artifacts due to the presence of rigid discs or ISC and also suggest the need for additional studies to evaluate the physiological relevance of deformability data obtained via these methods.
authors.affiliation: 1st Department of Medicine, School of Medicine, University of Pecs, Pecs, Hungary Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA, USA Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Miklos
authors.initials: M
authors.lastname: Rabai
authors.affiliation: Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA, USA Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Detterich
authors.affiliation: Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Rosalinda B
authors.initials: RB
authors.lastname: Wenby
authors.affiliation: Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA, USA.
authors.forename: Tatiana M
authors.initials: TM
authors.lastname: Hernandez
authors.affiliation: 1st Department of Medicine, School of Medicine, University of Pecs, Pecs, Hungary.
authors.forename: Kalman
authors.initials: K
authors.lastname: Toth
authors.affiliation: Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Meiselman
authors.affiliation: Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Wood
mesh_terms: D000755:Anemia, Sickle Cell / Q000097:blood*; D004907:Erythrocyte Deformability / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D013314:Stress, Mechanical
keywords: Laser diffraction ellipsometry; diffraction pattern; irreversible sickled cells; sickle cell disease; sickle erythrocytes