Background: Standard leucodepleted blood transfusions can induce the production of human leukocyte antigen (HLA)-specific antibodies, which are associated with longer transplant waiting times and poorer graft outcomes. We hypothesized that additional washing of leucodepleted red cells might reduce antigenic stimulus by removal of residual leukocytes and soluble HLA.
Methods: A retrospective review of HLA antibodies in children with chronic kidney disease stage 4-5 who had ≥ two HLA antibody screens between 2000 and 2009, pre- and post-transfusion, and were HLA antibody-negative at first testing. Patients were divided according to whether they received standard leucodepleted blood or "washed cells". To assess the efficacy of washing methods, total leukocytes were enumerated pre- and post- manual and automated washing of standard leucodepleted red cells that had been supplemented with whole blood to achieve measurable leukocyte levels pre-washing.
Results: A total of 106 children were included: 23 received no blood transfusions (group 1), six had washed cells only (group 2), 59 had standard transfusions only (group 3), and 18 had both standard and washed cells (group 4). Sensitization rates were 26, 17, 44, and 44 % in groups 1-4 (p = 0.32). Patients in groups 3 and 4 had more transfusions with red cells, platelets, and plasma products. There was no difference in HLA sensitization risk with washed or standard red cells on analysis of co-variance controlling for platelets and plasma transfusions. The red cell washing study showed no significant reduction in leukocytes using manual methods. Although there was a statistically significant reduction (33 %) from baseline pre-washing using the automated method, from 6.54 ± 0.84 × 10(6) to 4.36 ± 0.67 × 10(6) leukocytes per unit, the majority of leukocytes still remained.
Conclusions: There was no evidence that using washed leucodepleted red cells reduced patient HLA sensitization rates. Washing leucodepleted red cells is unlikely to reduce the risk of HLA sensitization due to the limited effect on residual leukocytes.