Donor leukocytes (from pRBCs or platelets) are associated with potential adverse reactions. First of all, their HLA surface antigens are main targets of the recipient’s immune system and can cause febrile transfusion reactions in the recipients. Furthermore, some viruses such as CMV, HTLV 1, and EBV are transmitted in donor leukocytes.
To prevent or at least decrease these adverse side effects, leukoreduction is utilized, removing > 99.99% of donor leukocytes via filtration. This filtration, called pre-storage leukoreduction, occurs shortly after donation and processing of the blood unit. There is also an option to perform leukoreduction filtration just prior to transfusion or at the patient’s bedside, this being referred to as post-storage leukoreduction. However, most data suggests that pre-storage leukoreduction is more effective for a variety of reasons. Pre-storage leukoreduction is performed by the blood supplier (i.e. Red Cross), while post-storage leukoreduction is performed by hospitals.
Reducing the transmission of viral disease in transfusions used to rely solely on serological screening assays. But now leukoreduction can reduce the transmission of CMV, HTLV I or EBV. Most of the studies have focussed on CMV transmission, since there is a high demand for CMV negative blood products for immunosuppressed patients, in whom CMV disease can be associated with high morbidity and mortality. Data suggests that leukoreduction is equivalent in preventing transmission of CMV as serological screening. Of special note, the transmission of viruses that are not exclusively carried intracellularly within leukocytes is not reduced by leukoreduction (such as HIV).
The anticipated benefit of reducing the transmission of variant Creutzfeldt-Jakob disease has not born out in the literature to date.
- Purported Benefits: reduce the transmission of CMV, HTLV I or EBV; reduce febrile transfusion reactions
- Prevalence: universal in Canada, Western Europe (including United Kingdom). More than 50% of units in the United States
- Data: universal leukoreduction cannot be supported. “Can’t hurt, may help” mentality must be balanced by increased costs
Howard L Corwin, James P AuBuchonIs leukoreduction of blood components for everyone? JAMA: 2003, 289(15);1993-5
E C Vamvakas, M A BlajchmanUniversal WBC reduction: the case for and against. Transfusion: 2001, 41(5);691-712
Paul C Hébert, Dean Fergusson, Morris A Blajchman, George A Wells, Andrew Kmetic, Doug Coyle, Nancy Heddle, Marc Germain, Mindy Goldman, Baldwin Toye, Irwin Schweitzer, Carl vanWalraven, Dana Devine, Graham D Sher, Leukoreduction Study InvestigatorsClinical outcomes following institution of the Canadian universal leukoreduction program for red blood cell transfusions. JAMA: 2003, 289(15);1941-9