This section covers the following modifications:
- Irradiation
- CMV Seronegative
- Leucodepletion (Filtration)
- Washing
Irradiation
What does this do?
Blood components that contain viable lymphocytes may be irradiated to prevent the proliferation of T-lymphocytes, which his the immediate cause of Transfusion-Associated Graft versus Host Disease (TA-GVHD). The minimum dose achieved in the irradiation field should be 25Gy, with no part receiving greater than 50Gy.
Shelf life impacts: taken from ANZSBT Guidelines for Gamma Irradiation of Blood Components revised 2003.
- Red Cells
Red Cells may be irradiated at any time up to 14 days after collection, and thereafter stored for a further 14 days from irradiation. Where the patient is at particular risk from hyperkalaemia, it is recommended that red cells be transfused within 24 hours of irradiation. [Red cells can re-enter the inventory as long as the altered shelf is observed]. - Platelets
Platelets can be irradiated at any stage in their five-day storage and can thereafter be stored up to their normal shelf life of five days after collection. - Granulocytes
Granulocytes for all recipients must be irradiated as soon as possible after production, and thereafter transfused with minimal delay.
When is this used?
See the ANZSBT Irradiation Guidelines
Other Information
The ANZSBT Guidelines for Gamma Irradation of Blood Components should also be used as a reference point for information on irradiation.
CMV Seronegative
What does this do?
For CMV-seronegative patients who are at risk for severe CMV disease. CMV-seronegative blood is selected by performing testing for antibodies to CMV, using a CMV test approved for donor screening. Transmission of CMV disease is associated with cellular blood components. FFP, cryoprecipitate and other plasma-derived blood components do not require special testing.
When is this used?
CMV-seronegative patients who are at risk for severe CMV disease due to:
- Receiving stem cell/bone marrow transplant
- Receiving highly immuno-suppressive chemotherapy
- Premature neonates
- Any pregnant women requiring transfusion, regardless of CMV status.
Refer to ANZSBT Guidelines for pretransfusion laboratory practice, Fifth edition, March 2007 – Section 2.6.
For indications where CMV negative blood components are required, the following is recommended:
Select CMV-seronegative components wherever possible.
If not available, leucocyte depleted components are considered to offer a high level of safety in preventing CMV transmission, but are not universally belileved to be equivalent to CMV seronegative components.
Careful monitoring for CMV infection and disease in high risk patients.
The additional benefit of leucocyte depletion in preventing transfusion transmitted CMV infection, in the context of the sole use of CMV seronegative components, is unknown.
ANZSBT Guidelines for pretransfusion laboratory practice, Fifth edition, March 2007. ASBT Guidelines for leucocyte depletion of blood and blood products, 1996. Bowden RA, et al. A comparison of filtered leucocyte-reduced and cytomegalovirus seronegative blood products for the prevention of transfusion-associated CMV infection after marrow transplant. Blood 1995; 86: 3598 – 3603. Nichols WG et al. Transfusion-transmitted cytomegalovirus infection after receipt of leukoreduced blood products. Blood, May 2003; 101:4195 – 4200. Vamrakas EC. Is white blood cell reduction equivalent to antibody screening in preventing transmission of cytomegalovirus by transfusion? A review of the literature and meta-analysis. Transfusion Medicine Reviews, Vol 19, No 3 (July) 2005: 185 – 199.
Leucodepletion (Filtration)
What does this do?
A unit of blood contains 1 – 10 x 109 leucocytes. Leucocyte depleted red cells and platelets contain <1 x 106 leucocytes per unit. Leucocyte depletion may be achieved during the collection process or by filtration soon after collection (pre-storage); after varying periods of storage in the laboratory or at the bedside. Currently washing is not a substitute for leucocyte depletion.
When is this used?
For patients requiring leucocyte depleted components.
Leucocyte depletion is not a substitute for irradiation.
For patients with repeated febrile non-haemolytic transfusion reactions due to HLA alloimmunisation or cytokine accumulation. May be used as primary prevention for this complication. Leucocyte depleted components are considered to offer a high level of safety in preventing CMV transmission, but are not universally believed to be equivalent to CMV seronegative components.
Washing
What does this do?
Washing removes unwanted plasma proteins, including antibodies.
There will be some loss of red cells.
When is this used?
For patients requiring red cells with a low protein supernatant.
Washing is not a substitute for leucocyte depletion.
Patients with reactions to transfused plasma proteins e.g. IgA deficiency. Patients with severe allergic reactions of unknown cause. May also be considered for severe reactions despite leucocyte depletion; patients with Paroxysmal Nocturnal Haemoglobinuria (PNH) who experience reactions despite group-specific leucocyte-depleted fresh red cells; rarely, for patients with T-activation when units from donors with low anti-T titres are not available or severe autoimmune haemolytic anaemia where excess complement may worsen destruction.
References
American Society of Anaethiologists Task Force on Blood Component Therapy. Practice guidelines for blood component therapy. Anesthesiology 1997; 84: 732-47.