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Int J Lab Hematol. 2012 Jun;34(3):311-9. doi: 10.1111/j.1751-553X.2011.01397.x. Epub 2012 Jan 25.

Role of gel test and flow cytometry in diagnosis of Coombs' negative autoimmune haemolytic anaemia.

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1
Clinical Pathology Department, Ain Shams University, Cairo, Egypt.

Abstract

INTRODUCTION:

This study evaluated the use of both gel test (GT) and flow cytometry (FC) techniques in the detection of red blood cell-bound immunoglobulin G (IgG) and, hence, the diagnosis of autoimmune haemolytic anaemia (AIHA) in cases that were negative by the conventional tube technique (CTT) direct antiglobulin test (DAT).

METHODS:

The study enrolled 50 clinically diagnosed AIHA patients with CTT Coombs' negative test and 55 control subjects. GT and FC were performed on both groups.

RESULTS:

Ninety-two percent (46/50) of patients were positive by GT. As for FC assay, the Receiver Operating Characteristic curve determined that a cut-off of 17.5% fluorescence was the best value for interpreting FC-DAT positively in the group of patients with haemolytic anaemia (100% sensitivity and specificity), while the best cut-off for mean fluorescence intensity (MFI) was 1.74, with 76% specificity and 96% sensitivity. Both mean percent fluorescence and MFI were significantly higher among patients when compared to controls (P < 0.001). FC assay results showed no statistically significant correlations with patients' laboratory data or GT grades (P > 0.05).

CONCLUSION:

Flow cytometry is more sensitive than GT for assessing CTT-DAT-negative AIHA. We propose that FC percent fluorescence cut-off values should be employed to determine the Coombs' negative AIHA cases.

[Indexed for MEDLINE]

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