BETHESDA, MD. – according to one researcher.
“We strongly feel that you should get an extended red cell type on the first encounter” for patients facing long-term transfusion support,, of the New York Blood Center, said at Sickle Cell in Focus, a conference held by the National Institutes of Health. “This can be a one-time test. It doesn’t have to be repeated.”
She also stressed the importance of ensuring that this information travels with patients, who may be seen at various hospitals. “One of the challenges here is making this part of the patient’s electronic medical record.”
Alloimmunization has been a major concern for chronically transfused patients, so there’s a real advantage to knowing a patient’s extended red cell antigen profile before the patient develops alloantibodies following transfusion, Dr. Westhoff said. Hemolytic transfusion reactions can sometimes destroy patients’ own RBCs in addition to the transfused RBCs. Having the patient’s profile to identify the potential cause of the incompatibility and guide transfusion support in an emergency can be lifesaving.
The implementation of genotyping by DNA-based methods has brought down the cost of this screening, making it no longer a barrier in care.
Dr. Westhoff cited a study she and her colleagues published on a study typing patients who have sickle cell disease (). In that paper, they found that DNA-based RBC typing provided improved accuracy and expanded information on RBC antigens, compared with hemagglutination methods. This led to its implementation as the primary method for extended RBC typing for patients with sickle cell disease at the Children’s Hospital of Philadelphia.
About 65%-70% of antibodies drop to levels that are not detectable by routine assays, further demonstrating the need for DNA-based methods. The drugs used to dampen the immune response in many of these patients may also hinder or impact detection of antibodies that remain at levels that continue to cause in vivo hemolysis, Dr. Westhoff said in an interview.
For patients with sickle cell disease in many Western countries, antigen matching for CEK, at a minimum, is routine. The United States is now moving in this direction.
“Modern transfusion practice is moving to knowing what antigens the patient is at risk to become immunized against. ... What antigens does the patient lack and what antibodies could the patient make,” Dr. Westhoff said in an interview. “It’s a major advantage in your transfusion service to expedite work-ups and patient care by having that extended antigen profile.”
Dr. Westhoff reported no relevant financial disclosures.