Hydroxyethylstarch sedimentation by gravity ex vivo for red cell reduction of granulocyte apheresis components

When selecting only leukocyte compatible donors, the requirement of ABO compatibility limits the investigation and application of granulocyte transfusion therapy by reducing the pool of potential donors. Ex vivo hetastarch (HES) sedimentation was evaluated as a method of red blood cell (RBC) reduction of granulocyte components. The objective was to determine if this procedure consistently resulted in reduction of component packed RBC (PRBC) volume to < 5 ml, the range acceptable for infusion of ABO incompatible blood components based on guidelines set forth by the American Association of Blood Banks (AABB).

HLA-matched, ABO-compatible sibling marrow donors were selected to donate granulocyte components, which were transfused into the allogeneic bone marrow transplant (BMT) recipient as prophylaxis against infection. Three granulocyte components were collected from each of 5 donors receiving G-CSF (daily x 5). Leukapheresis (LA) began 1 day after the first G-CSF dose (Day 1), and was repeated on Days 3 and 5. LA were performed using a continuous-flow blood cell separator, with 7L blood processed during each procedure. RBC sedimentation was facilitated by administration of a 6% HES solution to the donor line. The 5 granulocyte components collected on Day 1 were not manipulated after collection. The 10 components collected on Days 3 and 5 were manipulated by ex vivo gravity sedimentation for 60 minutes followed by transfer of the buffy coat (red cell poor [RCP] fraction) to a transfer bag with residual RBCs retained in the collection bag (red cell rich [RCR] fraction). The PRBC volume and cellular composition of the components and fractions were determined.

When data for the 10 manipulated components were combined, the fraction of the components with < 5 ml PRBC was 0.4 in the RCP and 0.1 in the RCR fractions. All unmanipulated components contained > 5 ml PRBC. The mean PRBC volume (ml) of the RCP and RCR fractions were 6.3 and 16.4, respectively (P = .06). The mean number of RBC (x10(11)) in the RCP and the RCR fractions were .41 and 1.73, respectively (P = .03). The average proportion of cells in the manipulated components lost to the RCR fraction was 19.2% of granulocytes and 18.6% of platelets.

Ex vivo HES sedimentation, as performed, significantly reduced the number of RBCs from granulocyte components, but did not consistently result in PRBC volumes in the RCP fraction within the range acceptable for infusion of ABO incompatible blood components based on the AABB guidelines. Moreover, significant numbers of granulocytes were lost to the RCR fraction.