A Primed Neutrophil Subset Predicts the Risk of Bloodstream Infections in Allo-HSCT Patients: A Prospective Study

Bloodstream infections (BSI) are the most common infectious complications in patients receiving allogeneic hematopoietic stem-cell transplants (allo-HSCT). Polymorphonuclear neutrophils (PMN) are quantified to monitor the susceptibility to BSIs, however, their degree of activation is not. We previously identified a population of primed PMNs (pPMN) with distinct markers of activation representing ∼10% of PMNs in the circulation. In this study, we investigate whether susceptibility to BSIs is related to the proportion of pPMN rather than strictly PMN counts. In this prospective observational study, we used flow cytometry to assess pPMNs in blood and oral rinse samples collected from patients receiving an allo-HSCT over the course of their treatment. We used the proportion of pPMNs in the blood on day five post-transplant to categorize patients into a high- or a low-pPMN group (> or