Background
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.
Methods
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 <10% pPMNs). These groups were then used as a predictor of BSIs.
Results
A total of 76 patients were enrolled in the study with 36 in the high-pPMN group and 40 in the low-pPMN group. Patients in the low-pPMN group had lower expression of PMN activation and recruitment markers and displayed a delay in PMN repopulation of the oral cavity after the transplant. These patients were more susceptible to BSI compared to patients in the high-pPMN group with an odds ratio of 6.5 (95% CI= 2.110-25.07, P= 0.002).
Conclusion
In patients receiving an allo-HSCT, having less than 10% pPMNs early in the post-transplant phase can be an independent predictor of BSI in allo-HSCT patients.