Direct blood fluorescence signal intensity of neutrophils (NEU-SFL): A predictive marker of death in hospitalized COVID-19 patients?

Introduction: Coronavirus disease 2019 (COVID-19) is a respiratory disease triggered by immunopathological mechanisms that cause excessive inflammation and leukocyte dysfunction. Neutrophils play a critical role in the innate immunity and are able to produce neutrophil extracellular traps (NETs: NETosis process) to combat infections. Some NETs markers are increased in patients who died from COVID-19. Recently, the neutrophil fluorescence variable (NEU-SFL), available on certain automated complete blood count (CBC) analyzers, has been correlated with NET formation and may reflect NETosis in patients. Here we evaluate whether NEU-SFL measured after admission of COVID-19 patients is associated with in-hospital survival or death. Patients and methods: 1,852 patients admitted for severe COVID-19 at Nîmes University Hospital in 2021 were retrospectively included in the study: 1,564 who survived the hospital stay and 288 who did not. The NEU-SFL was obtained on the Sysmex™ XN-10® analyzer and values for survivors and non-survivors were compared. The intra-patient NEU-SFL variations between the hospital entry and the last day of hospitalization were also analyzed (IRB 22.06.01, NCT05413824). Results: Non-survivors presented higher NEU-SFL values. NEU-SFL values above the 4th quartile were independently associated with a 2.88-fold risk of death. Furthermore, the difference of NEU-SFL values between the first and the last available data during hospitalization revealed that a decrease in NEU-SFL was associated to survivors and vice versa. Conclusion: Our study reinforces the role of neutrophils and NETosis in the pathophysiology and prognosis of COVID-19. Further studies combining NEU-SFL with other NETosis markers could improve the management of COVID-19 patients.

Use of platelet-rich plasma in regenerative medicine: technical tools for correct quality control.

BACKGROUND/AIMS: Platelet-rich plasma (PRP) injections are used in sports medicine and have been the subject of increased clinical interest. However, there have been very few reports of the composition of initial whole blood and the final PRP product. The objective of this study was to provide technical tools to perform a correct characterisation of platelets, leucocytes and red blood cells (RBCs) from whole blood and PRP. METHODS: Blood and PRP were obtained from 26 healthy volunteers and prepared according to the varying parameters encountered within PRP process preparation and quantification (harvesting method, anticoagulant used, sampling method, counting method). Concentrations were measured at t=0, t=1, t=6 and t=24 hours. RESULTS: Sampling of blood in Eppendorf tubes significantly decreased platelet concentration over time, whereas sampling in Microvette EDTA-coated tube kept platelet concentration stable until 24 hours. A non-significant difference was observed in platelet counts in PRP with impedance (median (IQR): 521.8 G/L (505.3-524.7)) and fluorescence (591.5 G/L (581.5-595.8)) methods. Other studied parameters did not influence platelet concentrations in blood or PRP samples. Leucocytes and RBC counts were similar whatever the anticoagulant, sampling, harvesting and counting methods used for both blood and PRP samples. CONCLUSIONS: Systematic sampling of blood and PRP in EDTA-coated tubes for quality control is recommended. The use of a validated counter for PRP sample should also be taken into account.

Visceral leishmaniasis in acute myeloid leukemia revealed on peripheral blood smear.

Images of parasitic forms of Leishmania infantum are typical in the hands of a skilled expert but should be known by biologists of Hematology Department. In an endemic region, the diagnosis of visceral leishmaniasis (VL) must be considered because of its potential role in accelerating hematological malignancy.