Functional State of Steroid- versus G-CSF-Mobilized Granulocytes: Considerations about the Storage of Granulocyte Concentrates for Neutropenic Patients

Background: High yields of granulocytes mobilized with G-CSF sparked new enthusiasm for transfusion in patients with severe neutropenia. The in vitro and in vivo function of granulocytes prior to and following storage was investigated. Material and Methods: Granulocyte concentrates collected from 10 donors receiving prednisone or G-CSF before leukapheresis were evaluated over 48 h of storage for differential blood count, pH, electrolytes, viability, phagocytosis, oxidative burst, and secretion of IL-1β, IL-6, IL-8 and TNFα. The follow-up of 5 transfused patients was monitored by blood counts, Creactive protein, and clinical outcome. Results: Compared to fresh granulocyte concentrates, no major changes in viability, phagocytosis, oxidative burst, and cytokine profile were seen in granulocytes stored overnight. In contrast, significant differences were observed after 48 h of storage. Steroid- and G-CSF-mobilized granulocytes showed no major differences in the first 24 h, except for changes in pH and IL-8 secretion. Transfusions of G-CSF-mobilized granulocytes stored overnight were well tolerated without additional adverse effects. Conclusion: G-CSF increased the yield of leukocytes 3.5-fold without enhancing side effects after granulocyte transfusions. The in vitro and in vivo function of G-CSF-mobilized granulocytes remained stable during storage for 24 h. Thus, the therapeutic use of G-CSF-mobilized granulocyte concentrates is facilitated by the possibility of overnight storage.