Successful granulocyte apheresis using medium molecular weight hydroxyethyl starch. 
Granulocyte transfusion (GTX) is a therapeutic option for severe bacterial or fungal infection in patients with sustained neutropenia after chemotherapy or stem cell transplantation.  However, high molecular weight hydroxyethyl starch (HES), which has been used for selective sedimentation of red blood cells during apheresis, is not easily available in many countries including Japan.  In this study, we evaluated the efficiency of granulocyte collection using medium molecular weight HES (130 kDa) in combination with the Spectra Optia apheresis system.  Apheresis was performed for 2 consecutive days from seven donors and the mean total neutrophil yield from the first and second apheresis was 5.27 ± 3.10 × 1010 and 2.91 ± 2.92 × 1010, respectively.  Infusion of concentrates from the first apheresis resulted in a significant neutrophil count increase and concentrates from the second apheresis were enough for maintenance of the neutrophil counts in all the recipients.  Although the number of cases is limited, our results clearly show that sufficient number of granulocytes can be harvested by using medium molecular weight HES and this strategy is a safe and effective clinical practice in countries where high molecular weight HES is not available.