Indications for Leucodepletion in Blood Transfusions
Leucodepletion is primarily indicated to prevent alloimmunization to HLA antigens, reduce febrile non-hemolytic transfusion reactions, and prevent cytomegalovirus transmission in specific patient populations. 1, 2
Primary Indications
- Patients with hematologic malignancies receiving chemotherapy, particularly those with acute myeloid leukemia (AML) receiving induction chemotherapy, to decrease the incidence of alloantibody-mediated refractoriness to platelet transfusion 1
- Hematopoietic stem cell transplant recipients (both allogeneic and autologous) to prevent HLA alloimmunization and reduce transfusion reactions 3
- Patients requiring long-term transfusion support (e.g., thalassemia patients) to prevent non-hemolytic febrile transfusion reactions and alloimmunization 4
- Prevention of cytomegalovirus (CMV) transmission in immunocompromised patients and neonates, with effectiveness comparable to using CMV-seronegative blood products 5
Secondary Benefits
- Reduction in transfusion reactions, particularly febrile non-hemolytic transfusion reactions 1, 4
- Decreased risk of transfusion-associated immunomodulation (TRIM) which can cause pro-inflammatory or immunosuppressive effects 6
- Potential reduction in postoperative infections in surgical patients 7
Patient Populations Requiring Leucodepletion
- Patients with acute myeloid leukemia from the time of diagnosis 1
- Patients with other types of leukemia receiving chemotherapy 1
- Patients undergoing hematopoietic stem cell transplantation 3
- Patients requiring multiple transfusions who are at risk for alloimmunization 4
- Immunocompromised patients at risk for CMV infection 5
Important Considerations
- Leucodepletion reduces white blood cells to <5 × 10^6 per unit (99.9% or log 3 reduction) 4
- Prestorage leucodepletion is the standard in the United States and many other countries, providing more consistent quality control 2
- Leucodepletion alone is not sufficient to prevent transfusion-associated graft-versus-host disease (TA-GvHD); irradiation of blood products is still required for this purpose 8
- Patients with congenital immunodeficiency states, Hodgkin's lymphoma, and those receiving certain therapies (purine analogues, anti-thymocyte globulin) require irradiated blood components to prevent TA-GvHD 1
Clinical Impact
- After implementation of leucodepletion for thalassemia patients, the incidence of non-hemolytic febrile transfusion reactions has been shown to decrease from 4% to 1% 4
- Universal prestorage leukoreduction has been shown to reduce rates of alloimmune refractoriness from 14% to 4% in patients receiving chemotherapy for acute leukemia or stem cell transplantation 3
Limitations and Considerations
- Leucodepletion via filtration can result in some platelet loss (up to 25-35%), which may increase the number of transfusion products required 2
- The evidence for leucodepletion to prevent death from any cause, infection, and other adverse events remains of low to very low quality 9
- While there is strong evidence for specific indications, universal leucodepletion for all transfusion recipients remains controversial 7, 9