Volume 47, Issue 7 pp. 1281-1289

Identification and quantification of fetal red blood cells in maternal blood by a dual-color flow cytometric method: evaluation of the Fetal Cell Count kit

Valérie Porra

Valérie Porra

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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Janine Bernaud

Janine Bernaud

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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Pierre Gueret

Pierre Gueret

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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Pascaline Bricca

Pascaline Bricca

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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Dominique Rigal

Dominique Rigal

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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Gilles Follea

Gilles Follea

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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Dominique Blanchard

Dominique Blanchard

From the French Blood Establishment, Nantes; French Blood Establishment, Lyon; CHU Rennes; and DB-BioRun, Nantes, France.

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First published: 02 May 2007
Citations: 48
Gilles Follea, Etablissement Français du Sang Pays de La Loire, 34 Bd Jean Monnet, BP n°91115, 44011 Nantes Cedex 1, France; e-mail: [email protected].

Abstract

BACKGROUND: As an alternative to the cumbersome Kleihauer-Betke test (KBT), flow cytometry represents a powerful method for the identification and quantification of fetal red blood cells (RBCs) in maternal circulation.

STUDY DESIGN AND METHODS: The aim of this study was to evaluate the Fetal Cell Count kit (IQ Products), an innovative flow cytometric method, based on the combination of antibodies directed, respectively, against fetal hemoglobin (HbF) and carbonic anhydrase (CA), a marker expressed after birth, to discriminate fetal RBCs from adult F cells containing HbF. The investigation was performed by two French laboratories that compared the data obtained by flow cytometry and KBT in 455 pregnant or just-delivered women as well as in 124 artificial mixtures containing from 0.01 to 5.00 percent cord cells.

RESULTS: The FL1/FL2 histogram allowed distinction between fetal RBCs (HbF+, CA–), F cells (HbF+, CA+), and adult RBCs (HbF–, CA+). The limits of detection and quantification were determined at 0.03 and 0.10 percent or 0.02 and 0.05 percent when analyzing 100,000 or 200,000 events, respectively. Linearity was demonstrated between 0.01 and 5.00 percent fetal cells in the mixtures (r = 0.95, p < 0.01). A good correlation between fluorescence-activated cell sorting (FACS) and KBT results was obtained with artificial mixtures (r = 0.94, p < 0.01). From the 405 Kleihauer-negative samples, none were identified as positive by FACS. Among the 50 Kleihauer-positive samples, 6 were shown not to contain fetal cells but F cells by FACS.

CONCLUSION: With this new dual-color flow cytometric method, accurate evaluation of fetomaternal hemorrhage was achieved even in the face of HbF of maternal origin.

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