Hirani Rena, Dean Melinda M, Irving David O
Australian Red Cross Lifeblood, Sydney, Australia.
School of Natural Sciences, Macquarie University, Sydney, Australia.
Vox Sang. 2025 Mar;120(3):310-314. doi: 10.1111/vox.13775. Epub 2024 Nov 25.
Leucoreduction is used to remove donor leucocytes during red blood cell (RBC) manufacture. However, not all are removed, and long-term survival of donor leucocytes, termed transfusion-associated microchimerism (TAM), has been shown to occur in some patients following RBC transfusion. The mechanism of TAM occurrence is unknown. One hypothesis is that viable donor haematopoietic cells remain within RBC units that could engraft. However, the analysis of cells remaining within leucoreduced RBC units has been minimal. This study aimed to isolate and analyse any residual leucocytes recovered from leucoreduced RBC units.
Leucoreduced RBC units were analysed on Day 1 (n = 4) and Day 42 (n = 4) post collection. Residual leucocytes were isolated using the EasySep™ RBC Depletion Reagent. Cell type analysis was conducted by flow cytometry using a leucocount reagent, a viability marker (7-amino-actinomycin D [7AAD]) and specific antibodies to CD45 and CD34. A representative 'pre-filter' sample was also obtained at the time of whole-blood donation to ensure expected cell counts across the donor samples.
Analysis of the pre-filter sample showed that CD45+/CD34+ cells accounted for 0.02%-0.07% of all leucocytes. Up to 253,850 residual leucocytes were isolated across both storage timepoints, and of these, up to 48 cells were CD45+/CD34+/7AAD-.
Viable CD45+/CD34+ cells were isolated from leucoreduced RBC units, indicating the potential for donor progenitor cells to be present during transfusion. Further characterization of these residual cells is required to explain how TAM may occur in some patients following RBC transfusion.
白细胞滤除用于在红细胞（RBC）制备过程中去除供体白细胞。然而，并非所有白细胞都能被去除，并且在一些患者接受RBC输血后，已证实供体白细胞的长期存活，即所谓的输血相关微嵌合体（TAM）会发生。TAM发生的机制尚不清楚。一种假说是有活力的供体造血细胞留存于可能发生植入的RBC单位内。然而，对白细胞滤除的RBC单位中留存细胞的分析极少。本研究旨在分离并分析从白细胞滤除的RBC单位中回收的任何残留白细胞。
对采集后第1天（n = 4）和第42天（n = 4）的白细胞滤除的RBC单位进行分析。使用EasySep™红细胞去除试剂分离残留白细胞。通过流式细胞术，使用白细胞计数试剂、活力标记物（7-氨基放线菌素D [7AAD]）以及针对CD45和CD34的特异性抗体进行细胞类型分析。在全血捐献时还获取了一个代表性的“预过滤”样本，以确保各供体样本的预期细胞计数。
预过滤样本分析显示，CD45+/CD34+细胞占所有白细胞的0.02% - 0.07%。在两个储存时间点共分离出多达253,850个残留白细胞，其中多达48个细胞为CD45+/CD34+/7AAD-。
从白细胞滤除的RBC单位中分离出了有活力的CD45+/CD34+细胞，表明输血过程中可能存在供体祖细胞。需要对这些残留细胞进行进一步表征，以解释RBC输血后某些患者中TAM可能如何发生。
