[Characteristics and mechanisms of action of leukocyte depletion filters].

Since their creation, leukocyte depletion filters, used to prepare leukocyte-poor red cell or platelet concentrates, have been continuously evoluting: their volume has been reduced and their composition has been modified, polyester fibers have replaced cotton wool or cellulose acetate. In the same way, their capacity to remove leukocytes has increased. The mechanisms of cell separation are still unclear. Through published studies, different factors seem to be implicated, such as wetable surface of the filter, surface tension or charge density of fibers. It was also observed that removal of lymphocytes from red cell concentrates is rather based on trapping in the fiber network, and that removal of granulocytes, monocytes and platelets is partly due to activation and subsequent adhesion to the fibers. There have been few studies of the mechanism of leukocytes depletion from platelets concentrates.