Article: A tale of two peripheral blood CD34+ cell counts: Evaluation of unexpectedly high values prior to peripheral stem cell collection
Authors: Kai J Rogers, Meredith G Parsons, Christopher S Strouse, Umar Farooq, Annette J Schlueter
Journal: Transfus Apher Sci. 2022 Dec 14;103624
Hematopoietic stem cells (HSCs) form the foundation of treatment for many hematologic and neoplastic diseases. The ability to collect HSCs that have been released into peripheral blood (PB) rather than harvesting from bone marrow (BM) directly has dramatically improved the likelihood of successful collection while minimizing donor discomfort . To facilitate the release of HSCs into PB, cytokines that stimulate cell proliferation and agents that directly antagonize stromal adherence factors are administered for several days pre-collection. The quantification of these mobilized HSCs is often performed pre-collection, based on the expression of the cell-surface marker CD34 . Importantly, CD34 expression is not restricted to HSCs; it is a general marker of immaturity, thus it is also useful in the diagnosis of hematologic malignancies such as myeloid/lymphoid leukemias and myelodysplastic syndromes. For HSC collection, the number of circulating CD34+ cells is useful in assuring adequate mobilization and may also be used to estimate the blood volume necessary to process to meet collection goals . To provide perspective, the mean pre-apheresis CD34+ cell count in autologous HSC donors at our institution from 2018 to 2021 was 47.3 cells/µl (median 35.3 cells/µl). Furthermore, < 10% of donors had CD34+ cell counts > 100 cells/µl, and the highest value was 465 cells/µl. This report details two autologous HSC donors with circulating CD34+ cell counts exceeding 1000 cells/µl, with differing treatment decisions following further investigation.
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