Guideline Key Points

A key point for clinicians is that blood product irradiation is associated with release of intracellular potassium from erythrocytes and in turn, decreases the shelf-life of the irradiated product

“The delay in availability of cellular blood products after irradiation is typically minimal and less than 30 minutes,” said Dr Sharma, explaining that irradiation is accomplished by using either gamma rays or x-rays. “The process of irradiation causes leakage of reactive oxygen species and intracellular potassium from erythrocytes and also damages the erythrocyte cell membrane, leading to a reduced shelf-life of the irradiated product.”

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She added that a dose of 25 Gy has been shown to completely inactive lymphocyte activity, but the standardized dose of radiation delivered varies between countries. “Irradiation is also associated with an increased cost,” she said.

Another key point was identifying patients who may be at the most risk for a reaction. “Individuals who would benefit from irradiated blood products the most are those with impaired cellular immunity, and those who have shared HLA antigen homology with the blood donor, placing them at risk of failing to recognize the transfused T lymphocytes as foreign,” said Jennifer Andrews, MD, MSc, an associate professor of pathology, microbiology and immunology (Division of Transfusion Medicine) and pediatrics (Division of Hematology/Oncology), and medical director of the blood bank at Vanderbilt University.

These groups, who are at risk of TA-GVHD, include:

  • Individuals with inherited defects in cellular immunity
  • Premature neonates
  • Recipients of intrauterine or neonatal exchange transfusions
  • Recipients of granulocyte transfusions
  • Individuals undergoing autologous or allogeneic hematopoietic stem cell transplantation
  • Individuals with Hodgkin lymphoma
  • Individuals treated with strong immunosuppressive therapies, such as purine analogues
  • Individuals who are receiving cellular blood products from a recipient who shares HLA antigen homology with them (eg, directed blood donation for a family member)

Another key point is that in clinical practice, “the differences in the definitions of impaired cellular immunity can lead to variable practice in terms of defining the populations who should receive irradiated blood products,” noted Dr Andrews.

“There is also variability in clinical practice regarding the timing of irradiation of the blood product, as some institutions irradiate the product immediately prior to usage, whereas others maintain an inventory of irradiated products,” she said.