Which of the following methods provides a leukocyte reduction during transfusion?

The method that provides leukocyte reduction during transfusion is the use of a log^3 leukocyte-removing filter. This specific filtering technique is designed to remove the majority of leukocytes from blood products before transfusion, significantly reducing the risk of febrile non-hemolytic transfusion reactions as well as potential complications associated with the transmission of certain infections, such as cytomegalovirus (CMV).

Leukocyte-reducing filters can lower the leukocyte count to less than 5 x 10^6 per unit of blood component, which is a standard requirement in many transfusion settings. The efficiency of these filters is based on a design that captures leukocytes while allowing the red blood cells or other components to pass through, effectively enhancing the safety of blood transfusions.

In contrast, washing with saline primarily helps to remove plasma proteins and antibodies but does not specifically target leukocyte reduction. Crossmatching ensures compatibility between donor and recipient blood types but does not influence the leukocyte count. Irradiation is used to prevent graft-versus-host disease but does not reduce leukocyte levels in the blood components. Each of these methods serves distinct purposes in blood transfusion practices, but only the log^3 leukocyte-removing filter