The use of flow cytometry may allow more accurate detection of red blood cell (RBC) autoantibody formation in patients with thalassemia compared with direct Coombs test, according to results reported in Hematology.
Regular RBC transfusions are the standard of care for patients with thalassemia. However, a major consequence of transfusion is the formation of alloantibodies and autoantibodies against RBC antigens that can result in hemolysis and difficulty in cross-matching of blood. The direct Coombs test is typically used to detect these immunoglobulin G (IgG) antibodies, but it is not particularly sensitive. Flow cytometry, on the other hand, has high accuracy, reproducibility, and sensitivity and therefore may have utility as a tool for detecting RBC-bound IgG.
Researchers collected blood samples from 59 polytransfused patients with thalassemia and 30 individuals without thalassemia. A persistent or transient positive direct Coombs test was seen in 8 patients with thalassemia (13.6%), whereas 34 patients (57.6%) had a positive flow cytometry (P <.001). There were 8 patients who were positive for both tests.
No differences were seen in gender, age at first transfusion, and previous period of transfusions between patients who had and did not have RBC-bound IgG. In addition, patients with these antibodies did not need more transfusions. However, 13 patients overall demonstrated increased RBC consumption in the 12 months after the study compared with 12 months before the study, and this increase was associated with positive flow cytometry (P =.026) and splenectomy (P =.024).
The researchers concluded that flow cytometry had higher sensitivity for detecting RBC-bound IgG compared with the direct Coombs test in polytransfused patients with thalassemia, and that “the presence of anti-RBC autoantibodies may cause an increase in transfusion requirements.” Furthermore, they noted that splenectomy is a risk factor for autoantibody formation.
1. Thedsawad A, Taka O, Wanachiwanawin W. Prevalence and clinical significances of red cell alloimmunization and red cell bound immunoglobulin G in polytransfused patients with thalassemias. Hematology. 2019;24:208-214. doi:10.1080/16078454.2018.1549818