Functional changes of neutrophils and monocytes by conditioning and filtration leukapheresis? (author's transl)

Abstract

Filtration leukapheresis (FL) is an effective and economic technique to collect large amounts of neutrophils for substitutional treatment of severe, transient neutropenia. An essential factor for effective granulocyte transfusion is functional integrity of the transfused cells. In this study eight hematologically normal donors were subjected to repetitive-cycle-Fl to examine functional changes of the collected neutrophils and monocytes compared to the donor's corresponding blood cells. After conditioning wit dexamethasone, increased neutrophil counts, increased percentage of band forms, decreased activity of leukocyte alcaline phosphatase, and decreased bactericidal activity were demonstrated. These changes indicate increased release of functional immature neutrophils of the nonproliferating bone marrow granulocyte pool. An increased latex-phagocytosis-index was noted during FL, signaling a cell stimulation, possibly by complement activation during Fl. The marked increase of latex-phagocytosis-indices of the eluted neutrophils was possibly induced by the neutrophils direct contact with the nylon fibers of the filter, resulting in mild degranulation, documented by the progressive but slight loss of bactericidal activity during FL. The indices of bactericidal activity were, however, not significantly different as compared to the values in the donor's blood. The repetitive-cycle-FL with minimal duration of contact between blood cells and nylon fibers of the filter, limits the process of degranulation and thereby technically reduces the functional alteration of donor granulocytes. Pretreatment of the donor with dexamethasone resulted only in a minimal change of functional integrity, caused by a transiently increased release of less mature neutrophils to the donor's blood.