Thrombopoietin in healthy donors

With concern we would like to react to the two Amgen-supported studies, presented in the September 1, 2001, issue of this journal, in which platelets harvested from thrombopoietin (TPO)–treated volunteer donors are used for prophylactic platelet support of chemotherapy-induced thrombocytopenia.1,2 We would have welcomed an accompanying editorial comment considering the ethics of TPO prescription in unrelated volunteer donors. Kuter et al1 mention the perception that single donor (SD) platelets are a better product compared to pooled random-donor concentrates as a rationale for the use of TPO for volunteer donors. There are, however, no data supporting the presumptions mentioned: the reduced exposure to different donors is a theoretical risk and not based on an increased incidence of transmitted infections; the risk of bacterial contamination is indeed increased in pooled platelets but influenced by production center and prevented by bacterial monitoring; the lower occurrence of febrile reactions to SD platelets is based on studies performed prior to leukoreduction and not confirmed by studies using leukoreduced platelets3; and the reduction in HLA-alloimmunization is based on a small and outdated study using non–leukocyte-depleted transfusions in which HLA-immunization was postponed (instead of reduced).4 It is curious that the authors do not quote a more recent extensive United States trial not confirming the advantage of SD platelets to prevent HLA-immunization and platelet refractoriness.5 

In the article by Goodnough et al2 it is concluded that the costs of apheresis may be reduced by splitting apheresis products with a high yield into 2 to 6 transfusion products. In the context of costs we would like to stress that in most parts of the world random pooled-platelet concentrates are still standard issue because of cost and existing infrastructures. Thrombapheresis is a bigger burden for the donor when compared to whole-blood donation because it is related to an increased risk for adverse events combined with longer duration of the procedure. Moreover, insufficient systematic follow-up studies have been performed to demonstrate that repeated exposure to extracorporeal circuit is inert.6 7 The fact that platelets are a perishable commodity will not be changed by administering TPO to healthy donors to increase the platelet yields of apheresis platelets, and thus we cannot follow this argument put forward by Kuter et al. The comparison with the use of other hematopoietic growth factors in healthy donors does not stand. Only recently granulocyte colony-stimulating factor (G-CSF) was accepted for use in healthy volunteer donors in Europe because of long-term experience in both patients and related healthy donors. We do not see any need for erythropoietin (Epo) administration to healthy volunteer donors outside the setting of autologous transfusions. In the case of both G-CSF and Epo, autoantibody induction has been proven to be extremely rare. The goal of blood transfusion service is to provide optimal safe blood products but not at the cost of increased risk to the donor. The proposition of administration of an unwarranted drug with unknown long-term side effects and potential “auto”-antibody inducing capacity upon multiple administrations to healthy unrelated volunteer donors should be withheld. Even if nonimmunogenic TPO will be developed, the blood transfusion services should refrain from administering this drug to volunteer donors until long-term experience in patients and possibly (as suggested by Kuter et al) in HLA-compatible related donors, in the case of HLA sensitization in patients with an extremely rare HLA phenotype, is accumulated as was the case with G-CSF.