What are the indications for irradiating blood products for transfusion?

Indications for Irradiating Blood Products

Blood products must be irradiated with a minimum dose of 25 Gy for stem cell transplant recipients (both autologous and allogeneic), patients receiving blood from partially matched family members, those with severe immunosuppression such as Hodgkin's lymphoma, and patients treated with fludarabine, other purine nucleoside analogs, antithymocyte globulin, or alemtuzumab. 1, 2

Primary Mechanism and Rationale

• Irradiation prevents transfusion-associated graft-versus-host disease (TA-GVHD), a rare but fatal complication with >90% mortality that occurs when viable donor lymphocytes mount an immune attack against recipient tissues 1, 3, 4
• Gamma irradiation damages DNA in contaminating lymphocytes, preventing cell division and subsequent immune attack 2
• Leukocyte depletion alone is insufficient to prevent TA-GVHD—gamma irradiation is mandatory 1, 2

Definitive Indications for Irradiated Blood Products

Stem Cell Transplant Recipients

• All autologous stem cell transplant recipients: from 7 days before stem cell harvest until 3 months post-transplant 2
• All allogeneic stem cell transplant recipients: from start of conditioning until at least 6 months post-transplant (extend duration if chronic GVHD develops) 1, 2, 5

Immunosuppressed Patients

• Hodgkin's lymphoma patients at all stages due to severe disease-associated immunosuppression 1, 2, 5
• Patients receiving fludarabine or other purine nucleoside analogs (cladribine, pentostatin) 1, 5
• Patients treated with antithymocyte globulin 1
• Patients receiving alemtuzumab (anti-CD52) 1, 5

Directed Donor Transfusions

• All blood products from partially matched family members whose WBCs are not rejected by the host immune system 1, 2
• All directed-donor products for potential stem cell transplant candidates 1

Products NOT Requiring Routine Irradiation

• Patients with acute leukemia receiving standard therapies (without the immunosuppressive agents listed above) 1
• Patients with AIDS 1
• Patients with solid tumors 1

Technical Specifications

• Minimum irradiation dose: 25 Gy as recommended by the British Commission for Standards in Hematology and AABB 1, 2, 5
• All cellular blood components require irradiation: red blood cells, platelets, and granulocytes 2, 5
• Both gamma-irradiation and X-irradiation are functionally equivalent for lymphocyte inactivation 6

Critical Implementation Pitfalls

• Approximately 30% of centers fail to irradiate routinely for consensus indications—clinicians must verify irradiation policies with their local blood suppliers 1, 2
• Many smaller centers lack blood irradiators and must send products to regional centers, causing transfusion delays 1, 2
• Some cancer centers with multiple providers irradiate all blood products routinely to guarantee vulnerable recipients receive proper products 1, 2
• Never assume leukoreduction alone is sufficient—it does not prevent TA-GVHD 1, 2

Additional Considerations for MDS Patients

• The NCCN guidelines show non-uniform consensus on routine irradiation for MDS patients 1
• However, all directed-donor products and transfusions for potential stem cell transplant candidates with MDS must be irradiated 1
• CMV-negative blood products are recommended whenever possible for CMV-negative recipients 1

Future Developments

• UV irradiation pathogen inactivation techniques (INTERCEPT and Mirasol) can damage lymphocyte DNA and prevent TA-GVHD, potentially eliminating the need for gamma irradiation in the future 1, 2, 7
• These technologies are approved in many countries but implementation varies 7