Introduction

Abstract

The presence of allogeneic leukocytes in blood products received little attention until the mid-1950s when these “passenger” cells were implicated in the etiology of febrile transfusion reactions, and early strategies based on centrifugation were developed to effect their removal. In recent decades and, particularly in the past five years, there has been an accumulation of literature implicating leukocytes in a wide variety of undesirable reactions to blood transfusion.