Human cells of healthy donors are a limited source for research and important for studying immune cell functions or biomarker identifications. Platelet collection by apheresis includes a leukocyte reduction system (LRS) to reduce immune competent cells. The LRS chamber is enriched with white blood cells and widely used as a source for research use. For platelet collection with Trima Accel® automated blood collection system, the software update to version 7 with a new algorithm may have an impact on leukocyte content and cell composition in the LRS chamber.

Platelet concentrates were obtained from healthy donors by apheresis with Trima Accel®, Terumo BCT using software versions 6 (v6) and 7 (v7). Cell collection was done either in autologous plasma (University Hospital Regensburg) or in additive solution (AS v7) T-PAS+ or Intersol (externally supplied). The LRS chamber was disconnected from the set system after apheresis and the cells were transferred to a tube. The volume was identified by pipetting. Cell concentration and leukocyte differentiation was done on an automated analyzer (Sysmex XN 550, Germany). Median values are shown in the text.

The aim of our study was to compare cell content in the LRS of Trima v6 to v7 and to consider the impact of collecting platelets in plasma versus AS. The volume with plasma v6 was 8.25 mL (n=16) as compared to plasma v7 with 8.20 mL (n=13) and AS v7 with 3.0 mL (n=14). WBC concentrations in plasma v6, plasma v7 and AS v7 were 113.95 x 103/µL, 157.75 x 103/µL and 64 x 103/µL, respectively. Erythrocytes and platelets remained comparable with 6.20 x 106/µL and 1.26 x 106/µL in plasma v6, 6.25 x 106/µL and 1.07 x 106/µL in plasma v7 and 7.50 x 106/µL and 1.17 x 106/µL in AS v7. Leukocyte composition was 2.6%, 2.4% and 8.5% neutrophils, 74.0%, 71.3% and 66.7% lymphocytes, and 22.6%, 23.4% and 23.6% monocytes in plasma v6, plasma v7 and AS v7 respectively.

The software adjustment of Trima Accel to v7 has no relevant impact on cell content and leukocyte composition in the LRS chamber produced by apheresis with plasma as cell suspension medium. However, when obtaining platelets in additive solution with Trima v7, the rinsing process leads to a clear volume reduction in the LRS and decreased absolute cell numbers. Additionally, the content of neutrophils was slightly increased. Thus, if high cell numbers are required LRS obtained from plateletpheresis with plasma may be preferred.

There is no conflict of interest.