Granulocyte Transfusion: Clinical Updates and a Practical Approach to Transfusion

PTP1B phosphatase dampens iPSC-derived neutrophil motility and antimicrobial function

Neutrophils are rapidly recruited to sites of infection and are critical for pathogen clearance. Therapeutic use of primary neutrophils has been limited, as they have a short lifespan and are not amenable to genetic manipulation. Human induced pluripotent stem cells (iPSCs) can provide a robust source of neutrophils for infusion and are genetically tractable. However, current work has indicated that dampened intracellular signaling limits iPSC-derived neutrophil (iNeutrophil) cellular activation and antimicrobial response. Here, we show that protein tyrosine phosphatase 1B (PTP1B) inhibits intracellular signaling and dampens iNeutrophil effector function. Deletion of the PTP1B phosphatase increased PI3K and ERK signaling and was associated with increased F-actin polymerization, cell migration, and phagocytosis. In contrast, other effector functions like NETosis and reactive oxygen species production were reduced. PTP1B-deficient neutrophils were more responsive to Aspergillus fumigatus and displayed rapid recruitment and control of hyphal growth. Accordingly, depletion of PTP1B increased production of inflammatory factors including the neutrophil chemokine interleukin-8. Taken together, these findings suggest that PTP1B limits iNeutrophil motility and antimicrobial function.

Granulocyte Transfusions in Neutropenic Infections: Insights From a Single-Center Study

Introduction Despite the development of modern antibiotic and antifungal therapies, neutropenic infections remain life-threatening. Granulocyte transfusion (GTX) is a less frequently used treatment modality in patients with refractory neutropenic infections. The role of donor GTX remains controversial, partly because of the lack of proper clinical trials. This study aimed to contribute to the literature by evaluating the efficacy and side effects of granulocyte transfusions in our center. Methods Eight febrile neutropenic patients with confirmed infections received granulocyte transfusions from ABO-compatible related and unrelated donors. Donors received filgrastim and dexamethasone stimulation, and granulocyte suspensions were irradiated and administered within six hours. Monitoring, antibiotic therapy, and granulocyte colony-stimulating factor (G-CSF) support were maintained. Results Our study observed a 28-day survival rate of 25%, which was lower than that reported in previous literature. The median number of transfusions was 3, with an average eight-day duration post-infection diagnosis, and no side effects were observed. Conclusion While some patients benefited from GTX, overall survival rates remained modest, indicating the need for further research. Prospective, well-powered randomized controlled trials are essential to address patient selection, dosing, and duration to determine the clinical utility of GTX. This study underscores the complexity of GTX in real-world clinical practice and provides insight into the ongoing debate regarding its efficacy in treating severe neutropenic infections.

Primitive genotypic characteristics in umbilical cord neutrophils identified by single-cell transcriptome profiling and functional prediction

The function and heterogeneity of neutrophils in neonatal umbilical cord blood (UCB) have not been characterized. In this study, we analyzed the neutrophils in UCB and healthy adults using single-cell RNA sequencing analysis for the first time. We found that neutrophils divided into six subpopulations (G2, G3, G4, G5a, G5b, and G5c) with different marker genes and different functions under homeostasis. Compared with healthy adults, neutrophils of UCB were more naïve and have more obvious degranulation and activation functions. Moreover, we found significant differences in the amount and function of G5b cells between healthy adults and UCB. The amount of G5b group in UCB was lower, but it has more degranulation, secretion and activation functions. In addition, we noted a new subset of G5c labeled by CD52, which almost did not exist in UCB. Besides, its differential genes were enriched in terms such as protein synthesis and mRNA transcription. Furthermore, uncharacteristic transcription factors ZNF-276, ZNF-319 and ZNF-354A were identified in our study. In summary, we first examined the heterogeneity and functional diversity of neutrophils in UCB, and these data provided new insights into the mechanism of neutrophil-mediated diseases of neonates and the wider use of neutrophils in UCB.