Abstract
Leukocyte viability (determined by e.g. propidium iodide [PI] staining) is automatically measured by hematology analyzers to check for delayed bench time. Incidental findings in fresh blood samples revealed the existence of leukocytes with decreased viability in critically ill surgical patients. Not much is known about these cells and their functional and/or clinical implications. Therefore, we investigated the incidence of decreased leukocyte viability, the implications for leukocyte functioning and its relation with clinical outcomes. An automated alarm was set in a routine hematology analyzer (Cell-Dyn Sapphire) for the presence of non-viable leukocytes characterized by increased fluorescence in the PI-channel (FL3:630±30nm). Patients with non-viable leukocytes were prospectively included and blood samples were drawn to investigate leukocyte viability in detail and to investigate leukocyte functioning (phagocytosis and responsiveness to a bacterial stimulus). Then, a retrospective analysis was conducted to investigate the incidence of fragile neutrophils in the circulation and clinical outcomes of surgical patients with fragile neutrophils hospitalized between 2013-2017. A high FL3 signal was either caused by 1) neutrophil autofluorescence which was considered false positive, or by 2) actual non-viable PI-positive neutrophils in the blood sample. These two causes could be distinguished using automatically generated data from the hematology analyzer. The non-viable (PI-positive) neutrophils proved to be viable (PI-negative) in non-lysed blood samples, and were therefore referred to as 'fragile neutrophils'. Overall leukocyte functioning was not impaired in patients with fragile neutrophils. Of the 11 872 retrospectively included surgical patients, 75 (0.63%) were identified to have fragile neutrophils during hospitalization. Of all patients with fragile neutrophils, 75.7% developed an infection, 70.3% were admitted to the ICU and 31.3% died during hospitalization. In conclusion, fragile neutrophils occur in the circulation of critically ill surgical patients. These cells can be automatically detected during routine blood analyses and are an indicator of critical illness.
Highlights
Neutrophils are the most abundant type of leukocyte found in the peripheral blood [1] and contribute to the host first line of defense against invading micro-organisms
Image stream analysis showed that the elongated neutrophil population was not caused by propidium iodide (PI) staining of nuclear or extracellular DNA, but caused by neutrophil autofluorescence, since intracellular fluorescence was observed in the absence of any fluorochromes including PI (Fig 1B)
Fragile neutrophils were found to be cells that were PI-negative in vivo and became PI-positive only after minimal manipulation in vitro
Summary
Neutrophils are the most abundant type of leukocyte found in the peripheral blood [1] and contribute to the host first line of defense against invading micro-organisms. A classic method to show the presence of dying leukocytes is staining of nuclear DNA with propidium iodide (PI). This method visualizes diminished membrane integrity as PI is impenetrable in healthy intact cells. The fraction of viable PI-negative leukocytes is assessed during every routine blood analysis by the Cell-Dyn Sapphire hematology analyzer (Abbott Diagnostics, Santa Clara, USA). This fraction is expressed as the white cell viability fraction (WVF) in the range 0–1 with 1 being 100% viable [6]. The WVF decreases with prolonged bench time and 0.95 is used as cut-off point for quality control of timely processing of blood samples [7]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
