Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a life-saving procedure used for the treatment of selected hematological malignancies, inborn errors of metabolism, and bone marrow failures. The role of neutrophils in alloHSCT has been traditionally evaluated only in the context of their ability to act as a first line of defense against infection. However, recent evidence has highlighted neutrophils as key effectors of innate and adaptive immune responses through a wide array of newly discovered functions. Accordingly, neutrophils are emerging as highly versatile cells that are able to acquire different, often opposite, functional capacities depending on the microenvironment and their differentiation status. Herein, we review the current knowledge on the multiple functions that neutrophils exhibit through the different stages of alloHSCT, from the hematopoietic stem cell (HSC) mobilization in the donor to the immunological reconstitution that occurs in the recipient following HSC infusion. We also discuss the influence exerted on neutrophils by the immunosuppressive drugs delivered in the course of alloHSCT as part of graft-versus-host disease (GVHD) prophylaxis. Finally, the potential involvement of neutrophils in alloHSCT-related complications, such as transplant-associated thrombotic microangiopathy (TA-TMA), acute and chronic GVHD, and cytomegalovirus (CMV) reactivation, is also discussed. Based on the data reviewed herein, the role played by neutrophils in alloHSCT is far greater than a simple antimicrobial role. However, much remains to be investigated in terms of the potential functions that neutrophils might exert during a highly complex procedure such as alloHSCT.

异基因造血干细胞移植（alloHSCT）是一种挽救生命的手术，用于治疗特定的血液恶性肿瘤、先天性代谢缺陷和骨髓衰竭。传统上，中性粒细胞在 alloHSCT 中的作用仅根据其作为抵御感染的第一道防线的能力进行评估。然而，最近的证据表明，中性粒细胞通过一系列新发现的功能，成为先天性和适应性免疫反应的关键效应器。因此，中性粒细胞正在成为高度通用的细胞，能够根据微环境及其分化状态获得不同的、通常相反的功能能力。在此，我们回顾了中性粒细胞在异基因造血干细胞移植（alloHSCT）不同阶段所表现出的多种功能的当前知识，从供体中的造血干细胞（HSC）动员到HSC输注后受体中发生的免疫重建。我们还讨论了作为移植物抗宿主病 (GVHD) 预防的一部分的 alloHSCT 过程中递送的免疫抑制药物对中性粒细胞的影响。最后，还讨论了中性粒细胞在异基因造血干细胞移植相关并发症中的潜在参与，例如移植相关血栓性微血管病（TA-TMA）、急性和慢性移植物抗宿主病（GVHD）以及巨细胞病毒（CMV）再激活。根据本文回顾的数据，中性粒细胞在 alloHSCT 中发挥的作用远远大于简单的抗菌作用。然而，就中性粒细胞在高度复杂的手术（例如异基因造血干细胞移植）中可能发挥的潜在功能而言，还有许多事情有待研究。