Leukapheresis: clinical experience and post-transfusion control

Abstract

The availability of platelet transfusion support to patients with bone marrow failure (such as aplastic anemia, or malignancy undergoing chemotherapy), has reduced the incidence of hemorrhage. However, infection then became the major cause of death in these patients [1]. There is an inverse relationship between the granulocyte count and the percent of days patients spend with infections [2]. Early studies showed that patients were at an increased risk of infection when the granulocyte count fell below 1000/µl [2]; although more recent data indicates that serious infection is not a problem until the granulocyte count falls below 500/µl [3]. One approach to the management of infection in patients with bone marrow failure is to replace depleted granulocyte stores by giving granulocyte transfusions. Because of the relatively small number of granulocytes in the circulation of normal people, early experience with granulocyte transfusions involved the use of patients with chronic myelogenous leukemia (CML) as donors [4]. Using large doses of granulocytes, increments in peripheral blood granulocyte count were observed and clinical improvement in the patients occurred a few hours following transfusion. Usually only one or two transfusions were necessary. During the early 1970’s there were many reports describing patients who improved following granulocyte transfusion. The reports concluded that granulocyte transfusions were useful, as evidenced by: a) clinical improvement following transfusions, often in patients previously unresponsive to antibiotics, and b) appearance of granulocytes in sites of infection which did not have an inflammatory response prior to transfusion. Because of this, there was great interest in making granulocyte transfusions widely available for use in treating granulocytopenic patients. This chapter will describe the methods presently available for granulocyte collection, the function of the cells collected and approaches to evaluating the effectiveness of the transfusions. The latter is especially important because as blood cell separators became available during the 1970’s, the source of granulocytes shifted from CML patients to normal donors. As a result, the dose of granulocytes transfused fell to approximately 10% of that used in earlier studies, and it became increasingly difficult to achieve obvious clinical benefits from a single transfusion [5]. Before considering granulocyte collection, it is appropriate to briefly review granulocyte production.