Leukocyte Reduction Fact Sheet

What are leukocytes?
Leukocytes are white blood cells, one of the types of cells in human blood. The body produces leukocytes to help fight off foreign substances in the body such as bacteria, viruses and abnormal cells in an effort to avoid sickness or disease. However, when leukocytes are transfused into another person, with red blood cells, platelets or plasma, they are not well tolerated and have been associated with some types of transfusion reactions.

What is leukocyte reduction?
Leukoreduction is the removal of contaminating white blood cells from blood products. The most common method of leukocyte reduction is filtration. In this process, blood is passed through a filter that separates leukocytes from other blood components, based on their size and stickiness.

There are three types of filtration that may occur:

  • Prestorage leukocyte reduction:
    • In this preferred process, filtration occurs at the blood center soon after the blood is collected and is performed using standardized, quality controlled processing methods designed to produce a consistent level of leukocyte reduction.
  • In-lab post-storage leukocyte reduction:
    • Filtration occurs after the blood has been delivered to the hospital.
  • Bedside leukocyte reduction:
    • Filtration occurs at the patient's bedside as the transfusion is being given.

What are the benefits of leukocyte reduction?
Leukocytes contained in whole blood can act as a contaminant when transfused into a recipient, causing reactions that range from mild to potentially harmful. Leukocytes in transfused blood have also been associated with more serious problems, such as transmission of certain viruses, including cytomegalovirus (CMV), a common virus affecting more than half of all North Americans, and human T-cell lymphotropic virus (HTLV-I/II) which may cause blood or neurological diseases. Leukocytes have been known to cause the formation of antibodies that make future transfusions less likely to be effective and more likely to cause an adverse reaction.

By removing leukocytes from whole blood, the incidence rates for febrile (fever) transfusion reactions are significantly reduced for patients susceptible to this reaction, and may result in improved patient outcomes, shorter hospital stays and reduced health care costs.