A simple laboratory alternative to irreversibly sickled cell (ISC) counts

Area of Science:

• Hematology
• Cell Biology
• Biophysics

Background:

• Irreversibly sickled cells (ISC) are a key feature of sickle cell disease (SCD).
• Quantifying ISC in peripheral blood smears is inconsistent and complicates understanding their role in disease variability.
• Standardized ISC quantification is crucial for assessing SCD severity and treatment efficacy.

Purpose of the Study:

• To develop and validate alternative, objective methods for quantifying ISC in SCD patients.
• To establish reliable measurements that correlate with traditional ISC counts but offer greater standardization.
• To explore the utility of cell density and deformability as surrogates for ISC quantification.

Main Methods:

• Analysis of whole blood samples using a two-step density gradient in a microhematocrit centrifuge.
• Ektacytometry to measure red blood cell deformability.
• Correlation analysis between density measurements, deformability, and morphologically identified ISC percentages.

Main Results:

• A strong correlation was observed between the proportion of high-density cells and the percentage of morphologically identified ISC.
• Ektacytometric measurements of cell deformability also showed a strong correlation with ISC counts.
• Both density and deformability measurements reflect the unique physical properties of ISC, such as low water content and high MCHC.

Conclusions:

• Density gradient analysis and ektacytometry provide objective and reproducible methods for quantifying ISC.
• These novel measurements can serve as reliable substitutes for subjective microscopic counting of ISC.
• Objective ISC quantification can improve the assessment of disease severity and variability in sickle cell disease.