Use of the Gel Test to Follow Up Chimerism in ABO Mismatched Bone Marrow Transplantation Patient: A Case Report
Rachata Lumkul MD*, Oytip Nathalang PhD**, Pasra Arnutti MSc**, Aree Janyatham RN*, Kitti Torcharus MD*, Triroj Krutvecheo MD*, Thip Sriphaisal MD*
Affiliation : * Hematology-oncology Division, Department of Pediatrics, Phramongkutklao Hospital ** Department of Pathology, Phramongkutklao College of Medicine
Objective : The authors report here our experience using the gel test to follow up chimerism in a 5 year
old girl with β thalassemia/Hemoglobin E disease (β thal/HbE), post allogeneic bone marrow transplantation
with Hb E trait HLA identical sibling donor. They were ABO blood group major mismatched donor-
recipient pairs (donor and recipient blood group are B and O, respectively).
Materials and Methods : Pre and post transplanted EDTA blood samples from the girl with β thalassemia/
Hemoglobin E were tested for ABO, Rh and direct antiglobulin test (DAT) using the A-B-AB-D-ctl/
AHG card and the titer of anti-A and anti-B were tested by the conventional tube technique. The sex
chromosome study and hemoglobin typing were also examined.
Results : In this technique, mixed field agglutination is clearly identified from positive and negative
results. The authors detected peripheral recovery, mixed O/B population after transplantation on day +26
with positive DAT. The DAT was negative on day +67 after transplantation and the recipient blood
group was completely changed to B on day +123. In addition, Hb typing was changed to Hb E trait with
Hb F less than 5 % on day +37. The engraftment of neutrophils, more than 5x109/L, was detected on
day+14 and platelet count was more than 20x109/L on day +28. On day +90, the patient was transfusion-
independent with the mean Hb level at 11.4 g/dL (10.4-13.1). The sex chromosome and hemoglobin
typing were changed to the donor on day +300.
Conclusion : The gel test is an alternative method which is simple and helpful in detecting mixed red
blood cell populations, particularly in the ABO or other blood group mismatched bone marrow
transplantation.
Keywords : Gel test, Chimerism
