Is irradiated blood necessary for transplant patients?

Irradiated Blood Products for Transplant Patients

Yes, irradiated blood products are necessary for transplant patients to prevent transfusion-associated graft-versus-host disease (TA-GVHD), which is rare but usually fatal. 1

Rationale and Mechanism

• TA-GVHD occurs when viable donor lymphocytes in blood products mount an immune attack against the recipient's tissues, which can be prevented by gamma irradiation of blood products 1
• Leukocyte depletion alone is insufficient to prevent TA-GVHD; gamma irradiation with a minimum dose of 25 Gy is required to inactivate T lymphocytes 1
• The irradiation damages DNA in contaminating lymphocytes, preventing cell division and subsequent immune attack 1

Patient Populations Requiring Irradiated Blood Products

Transplant Patients:

• All recipients of autologous and allogeneic stem cell transplants require irradiated blood products 1
• For allogeneic HSCT: from start of conditioning until at least 6 months post-transplant (longer if chronic GVHD develops) 1
• For autologous HSCT: from 7 days before stem cell harvest until 3 months post-transplant 1
• Some centers provide irradiated products as soon as a patient is identified as a potential HSCT candidate 1

Other High-Risk Patients:

• Patients receiving blood products from partially matched family members 1
• Patients with severe immunosuppression (e.g., Hodgkin's lymphoma) 1
• Patients receiving immunosuppressive therapy with drugs such as fludarabine, other purine nucleoside analogs, antithymocyte globulin, or alemtuzumab (anti-CD52) 1

Implementation Guidelines

• All cellular blood components (red blood cells, platelets, granulocytes) must be irradiated to 25 Gy 1
• Both the British Commission for Standards in Hematology and the AABB recommend irradiation for these high-risk populations 1
• Plasma and plasma derivatives do not require irradiation as they do not contain viable lymphocytes 2

Clinical Considerations

• TA-GVHD symptoms include fever, pancytopenia, skin rash, desquamation, severe diarrhea, and liver function abnormalities 1
• It may be difficult to distinguish TA-GVHD from radiation-induced organ toxicity or transplant-related GVHD 1
• The mortality rate for TA-GVHD is approximately 90% 3

Practical Challenges

• Many smaller centers do not have blood irradiators and must send products to larger regional centers, causing potential delays 1
• Survey data shows significant heterogeneity in irradiation practices, with approximately 30% of centers not routinely irradiating for consensus indications 1
• Some cancer centers irradiate blood products for all patients to ensure vulnerable recipients receive proper products 1

Future Considerations

• UV irradiation pathogen inactivation techniques may potentially eliminate the need for gamma irradiation of platelet products in the future 1
• These techniques can damage DNA in contaminating lymphocytes, preventing cell division and subsequent TA-GVHD 1

Common Pitfalls and Caveats

• Failure to communicate with blood banks about patients requiring irradiated products 1
• Assuming leukoreduction alone is sufficient (it is not) 1
• Not recognizing all high-risk patient groups beyond just transplant recipients 1
• Discontinuing irradiated products too early after transplantation 1, 4
• Not considering irradiation for patients receiving blood from first-degree relatives 5

Clinicians should be aware of their local blood bank's irradiation policies and maintain clear communication about patients requiring irradiated products to prevent this rare but fatal complication.