Transfusion medicine handbook

2. Collection, Testing and Processing of Blood Donation

2.10 Leucodepletion

All blood components for direct clinical transfusion are leucodepleted. Leucodepletion is a process for removing white cells (leucocytes) from blood components. This is achieved by means of a special filter or by differential centrifugation. Leucodepleted blood components should contain < 5 x 10⁶ white cells per unit.

NZBS introduced universal prestorage leucodepletion in July 2001, initially as one of a series of precautionary measures against the potential risk of transmission of variant Creutzfeldt-Jakob disease (vCJD) by blood transfusion.

There is good evidence to support the value of leucodepletion in preventing transfusion-associated transmission of some infectious agents and in reducing some of the adverse immunomodulatory effects of allogeneic transfusion:

• Reduction in frequency of febrile non-haemolytic transfusion reactions.
• Prevention or delay of alloimmunisation to human leucocyte antigens.
• Prevention or delay of platelet refractoriness due to alloimmunisation.
• Reduction in the risk of CMV transmission.

Leucodepletion also has other theoretical advantages:

• Reducing the risk of other leucocyte-associated blood borne infections, such as transmission of HTLV-I/II, and inadvertent bacterial contamination of blood components.
• May reduce the risk of perioperative infection or cancer recurrence by reducing the immunomodulatory effects of blood transfusion.
• May prevent some cases of transfusion related acute lung injury (TRALI).