Flow cytometric osmotic fragility--an effective screening approach for red cell membranopathies.

BACKGROUND

Among the red cell membrane disorders, hereditary spherocytosis (HS) is one of the most common causes of inherited hemolytic anemia. The aim of this study was to compare the flow-cytometric approach for screening of red cell membrane disorders based on osmotic fragility with the eosin-5-maleimide (E5'M) dye test. A group of β-thalassemia heterozygotes were also studied.

METHODS

A red cell suspension was spiked with deionized water during acquisition and the count of residual red cells measured sequentially in real-time using flow cytometry. Fluorescence intensity of red cells stained with eosin-5-maleimide was also measured.

RESULTS

The hereditary spherocytosis (HS) group showed significantly decreased percentage residual red cells (9.31% ± 3.75%) (P = 0.0091) whereas the β-thalassemia group showed a significant increase (93.56% ± 12.98%) (P = 0.0008) compared to the normal control group (46.26% ± 11.33%). The cut off value of the flow cytometric osmotic fragility (FCM OF) test for red cell membrane disorders was 23.59% giving a sensitivity of 100% and specificity of 98%.

CONCLUSIONS

The advantages of the FCM OF test are that it is quantitative, time effective and requires only deionized water for the measurement of osmotic fragility. It could be an effective first line screening approach for red cell membrane disorders in hematology laboratories where a flow cytometer is available.