Leukocyte Reduction

The process of removing white blood cells from a blood product prior to transfusion, primarily by filtration. So-called “leukocyte reduction filters” are part of a whole blood collection bag set, so that after a unit of blood is collected, it can be quickly filtered without breaking the sterility of the product. Modern apheresis equipment has built-in leukocyte reduction capability, as well, so products collected via apheresis are almost always leukoreduced. The FDA has established standards to define whether or not a unit of a particular product is “leukoreduced”; these standards are covered in discussion of the individual products elsewhere in the glossary (see Leukocyte-reduced Red Blood Cells, Leukocyte-reduced Platelets, Leukocyte-reduced Apheresis Platelets).

There are three well-accepted reasons to leukocyte-reduce blood products:

  • Prevention of alloimmunization to foreign HLA antigens
  • Prevention of febrile nonhemolytic transfusion reactions
  • Prevention of CMV transmission (though this one is admittedly still debated)

Many also believe that leukoreduction helps prevent the immunosuppression that occurs after transfusion (so-called “transfusion-related immunomodulation, or “TRIM”). Leukocyte reduction may also play a role in decreasing bacterial contamination of blood products, and prevention of transmission of prions (such as the vector of variant Creutzfeldt-Jakob disease), though these are less accepted indications.

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