Assessment of erythrocyte shape by flow cytometry techniques
Michael Piagnerelli 1, Karim Zouaoui Boudjeltia 2, Dany Brohée 3, Anne Vereerstraeten 3, Pietrina Piro 3, Jean-Louis Vincent 1* and Michel Vanhaeverbeek 2
1 Erasme University Hospital, Belgium
2 CHU Charleroi-A Vésale Hospital, Belgium
3 CHU Charleroi-A. Vésale Hospital, Belgium
* To whom correspondence should be addressed. E-mail: jlvincent{at}ulb.ac.be.
Accepted 11 May 2006
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Abstract |
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Background: Red blood cell (RBC) rheology is altered in different diseases, including acute conditions such as the intensive care unit (ICU) patient with sepsis or with an inflammatory reaction due to postoperative states or intracerebral haemorrhage, or chronic conditions like diabetes mellitus or terminal renal failure.
Several techniques are available to assess alterations in RBC rheology, especially deformability, but they are too cumbersome to be used on a large number of cells. Therefore, we developed a new, rapid flow cytometry technique for easy assessment of RBC shape in patients.
Methods: In flow cytometry, healthy human RBC shape shows a bimodal distribution related to the biconcave form. On this histogram, we calculated the second Pearson coefficient of dissymmetry-PCD- representing the asymmetry of this histogram- and the spherical index (M2/M1), both representing the spherical shape. We used this technique in healthy volunteers (n = 17) and in diseases characterized by abnormalities in RBC rheology including: terminal renal failure requiring haemodialysis (n = 28), diabetes mellitus ( n = 18), sepsis (n = 19) and acute inflammatory states (postoperative, intracerebral haemorrhage, chronic obstructive pulmonary disease, epilepsy or severe drug intoxication; n = 21). Multivariate analysis was
performed to determine factors influencing RBC shape.
Results: Measurement of RBC shape was highly reproducible. We observed a good correlation between the PCD and the spherical index except in the non-septic critically ill patients. RBCs were more spherical in patients with terminal renal failure (PCD: -0.56 ± 0.14,
p< 0.05), diabetes mellitus (PCD: -0.59 ± 0.23, p < 0.05), sepsis (PCD: -0.58 ± 0.22, p < 0.05) or an acute inflammatory state (PCD:-0.65 ± 0.29, p < 0.05) than in healthy volunteers (PCD: -0.89 ± 0.12).
The spherical index was also increased in all populations compared to healthy volunteers (terminal renal failure: 2.30 ± 0.20; diabetes mellitus: 2.27 ± 0.38; sepsis: 2.28 ± 0.37; acute inflammatory state: 2.35 ± 0.42 versus healthy volunteers: 2.72 ± 0.47; all p < 0.05).
Multivariate analysis demonstrated that the underlying pathology (sepsis, acute inflammatory
state, diabetes mellitus, terminal renal failure) was the principal cause of these RBC shape abnormalities.
Conclusion: RBCs are characterized by an increased spherical shape in many disease states.
The measure of the second Pearson coefficient of dissymmetry in flow cytometry is a new, easy method to investigate RBC shape in various diseases. This technique could facilitate the investigation of abnormalities of RBC rheology.
Key Words:
flow cytometry, red blood cell, sepsis, shape, spherical index
