In the context of this article, alloimmunization refers to the immune response mounted by a donor recipient to foreign, transfused, blood cell antigens; this occurs when donor blood is not closely enough matched to the recipient. Alloimmunization results in a transfusion reaction (immediate or delayed) during which symptoms might include back pain, chills, dizziness and fainting. The reactions can range from mild to life-threatening in severity.
It is estimated that the alloimmunization rate of frequently transfused patients in the US is approximately 36%.
These patients receive multiple transfusions due to disorders such as sickle cell disease and thalassemia. In a recent study on alloimmunization in sickle cell sufferers, it was found that 58% of chronic and 15% of episodically transfused patients were alloimmunized (1).
Hospitals, blood banks and transfusion centers traditionally rely on serology tests to phenotype patients and donors, and enable matched blood to be transfused. Some laboratories have been using in-house developed and RUO molecular tests to gain additional information on patient genotype; however this is time consuming, complex and impractical for anything other than occasional use in specialist cases.
It can be difficult to find licensed antisera for rare antigens, and when antisera does exist, it is often in limited supply. Serology tests can also be notoriously difficult to interpret in the months following a transfusion when a dual red cell population is present in the blood stream.
The PreciseTypeTM HEA (human erythrocyte antigen) assay is the first-ever HEA assay which uncovers the specific gene variants associated with RBC antigens, enabling clinical scientists to provide the closest possible match between donor and recipient. The assay uses the 24 known gene mutations to identify 35 red blood-cell antigens
from 11 blood groups simultaneously.
In the clinical laboratory, the assay could be used to create a phenotypic profile of a patient before they ever receive any transfused blood. If donor blood is similarly profiled at the donor center/blood bank, fully matched blood could always be provided. If a patient has already received multiple transfusions, a molecular profile would still be extremely useful to identify the best-matched donor blood.
The PreciseType HEA test will be available to customers this summer; a RUO version has been available since 2005. The test is a multiplex assay; running the test takes approximately six hours for up to 96 samples.
Discover how this development could have a significant impact on patients like Trey: watch video.
Read the full press release regarding FDA approval here.
(1) High prevalence of red blood cell alloimmunization in sickle cell disease despite transfusion from Rh-matched minority donors.