Evaluation of flow cytometric enumeration of foetal erythrocytes in maternal blood.
In pregnant women subject to abdominal trauma or other foetomaternal haemorrhage, foetal red blood cells containing haemoglobin-F (HbF) can be found in the circulation. Recently, a monoclonal antibody to HbF has become commercially available, enabling application of a flow cytometric immunofluorescence method for accurately determining the concentration of HbF+ red blood cells. We demonstrate that white blood cells are included in the cluster selected as red blood cells and that these white blood cells exhibit a level of autofluorescence that coincides with the fluorescence signal from HbF+ red blood cells. However, these white blood cells can be excluded from the analysis, thus preventing spuriously increased HbF+ red blood cell counts. We present the results of patient samples containing HbF+ red cells as illustrations of the technique and as a potential interference by HbF-containing cells of nonfoetal origin. Using samples spiked with cord blood, the method is exactly linear with a high coefficient of correlation (r=0.997). Furthermore, the assay has excellent precision (CV < 2.4%), a low limit of detection (0.12% HbF+ RBC), is independent of Rhesus D and can be completed within 1.5 h. This method is suitable for accurate determination of foetomaternal haemorrhage.
Janssen
W C M
WC
Department of Clinical Laboratories, Catharina Hospital, Eindhoven, The Netherlands.
Hoffmann
J J M L
JJ
D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D016477:Artifacts; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D005319:Fetal Hemoglobin / Q000032:analysis* / Q000276:immunology; D005331:Fetomaternal Transfusion / Q000097:blood; D005434:Flow Cytometry / Q000379:methods*; D005470:Fluorometry; D006801:Humans; D007962:Leukocytes / Q000737:chemistry; D008297:Male; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood; D012203:Rh Isoimmunization / Q000097:blood / Q000209:etiology; D012204:Rh-Hr Blood-Group System / Q000032:analysis; D012680:Sensitivity and Specificity; D017086:beta-Thalassemia / Q000097:blood
D000911:Antibodies, Monoclonal; D012204:Rh-Hr Blood-Group System; D005319:Fetal Hemoglobin