Usefulness of the New Hematological Parameter: Reactive Lymphocytes RE-LYMP with Flow Cytometry Markers of Inflammation in COVID-19

Performance evaluation of the new Sysmex XR-Series haematology analyser

Background

The new XR-Series haematology analyser from Sysmex provides increased throughput and automation, along with a new reagent in WDF channel for optimised WBC differential.

Methods

An analytical performance study for the XR analyser was conducted to evaluate the WDF channel parameters in comparison to the instrument specifications. Additionally, 7460 samples were measured on XR and XN analysers to compare selected parameters and flags, and 930 randomly selected samples were further evaluated with microscopy.

Results

All investigated aspects of the analytical performance study for the XR fell within the manufacturer specifications. The correlation coefficients between the two systems for the parameters tested were greater than 0.983 for the main CBC and DIFF parameters, greater than 0.909 for the Extended Inflammation Parameters, and greater than 0.932 for the parameters used in the workflow rulesets of the Extended IPU. Similarly high sensitivities for the detection of abnormal cells were observed for the 'Blasts/Abn Lympho?' flag (XN: 100%, XR: 99.0%) and WPC abnormal flags ('Blasts?' or 'Abn Lympho?') (XN: 97.0%, XR: 96.0%). XN with WPC channel had a 26% reduction of false positive smears compared to XR with 22% reduction, a statistically non-significant difference.

Conclusion

The XR analyser had very good analytical performance, and highly comparable results to the predecessor XN analyser in all investigated parameters, flags and workflow aspects.

Analysis of Leukocyte Subpopulations by Flow Cytometry during Hospitalization Depending on the Severity of COVID-19 Course

The mechanisms underlying the immune response to coronavirus disease 2019 (COVID-19) and the recovery process have not been fully elucidated. The aim of the study was to analyze leukocyte subpopulations in patients at significant time points (at diagnosis, and 3 and 6 months after infection) selected according to the analysis of changes in the lungs by the CT classification system, considering the severity of the disease. The study groups consisted of severe and non-severe COVID-19 patients. There was a significant decrease in CD8+ T cells, NK and eosinophils, with an increasing percentage of neutrophils during hospitalization. We noticed lower levels of CD4 and CD8 T lymphocytes, eosinophils, basophils, and CD16+ monocytes and elevated neutrophil levels in severe patients relative to non-severe patients. Three months after infection, we observed higher levels of basophils, and after 6 months, higher CD4/CD8 ratios and T cell levels in the severe compared to non-severe group. Non-severe patients showed significant changes in the leukocyte populations studied at time of hospitalization and both within 3 months and 6 months of onset. The CT CSS classification with parameters of the flow cytometry method used for COVID-19 patients determined changes that proved useful in the initial evaluation of patients.

Intermediate Monocytes with PD-L1 and CD62L Expression as a Possible Player in Active SARS-CoV-2 Infection

Monocytes play a role in viral biology, but little is known about the monocyte subpopulation in the course of COVID-19 disease. The aim of the study was the analysis of classical, intermediate and non-classical monocytes with expression of PD-L1 and CD62L, TIM-3 and CD86 molecules in peripheral blood (PB) to distinguish patients with SARS-CoV-2 infection from convalescent patients. The study group consisted of 55 patients with SARS-CoV-2 infection and 51 convalescent patients. The cells were analyzed by flow cytometry. The number and proportion of monocytes were lower in patients with COVID-19 than convalescent patients. We observed a lower proportion of non-classical monocytes in COVID-19 patients than convalescent ones. There was a higher proportion of PDL-1-positive intermediate monocytes in COVID-19 patients than convalescent ones. We noticed a higher geometric mean fluorescence intensity (GeoMean) of PD-L1 on intermediate monocytes in COVID-19 patients than convalescent patients, and a higher proportion of CD62L-positive monocytes in COVID-19 patients in comparison with convalescent ones. We found a higher GeoMean of CD62L on monocytes in COVID-19 patients than convalescent ones. Assessment of PD-L1- and CD62L-positive monocyte subsets may identify patients with a possible predisposition for rapid recovery. The monitoring of monocyte subsets in PB might be a useful test in COVID-19 patients.

Neutrophil-to-lymphocyte ratio and mean platelet volume in the diagnosis of bacterial infections in COVID-19 patients. A preliminary analysis from Ecuador

INTRODUCTION

Hospitalized COVID-19 patients are at risk of hospital infection. The neutrophil-to-lymphocyte ratio (NLR), lymphocyte-C-reactive protein ratio (LCR) and mean platelet volume (MPV) are established inflammation markers reflecting the systemic inflammatory response. The objective of this study was to evaluate the clinical characteristics of patients with COVID-19 and bacterial co-infections, as well as the correlation with NLR and MPV.

METHODS

We assessed the role of the NLR and MPV in diagnosing bacterial infections in COVID-19 patients. The Wilcoxon test was used to compare the mean NLR and MPV between the diagnostic evaluation moments, while the Mann-Whitney test was used to compare NLR and MPV by sex and age.

RESULTS

The NLR was compared three days before the culture and the day of taking the culture, observing significant differences (p=0.020). MPV three days before the culture and the day of the culture were compared, also observing significant differences (p=0.031). NLR and MPV were compared at the different evaluation times according to sex and age group, observing for the age group significant differences for the NLR three days before the culture (p=0.004).

CONCLUSION

In our study, there were significant differences in NLR and MPV between the three days before culture and the day of culture. It is advisable to continue to enrol more patients in the study so that in the future, we can add results on the diagnostic accuracy of the NLR and MPV in the timely diagnosis of bacterial infection in patients with COVID-19.

Neutrophil Maturation, Reactivity and Granularity Research Parameters to Characterize and Differentiate Convalescent Patients from Active SARS-CoV-2 Infection

Studying the dynamics changes of neutrophils during innate immune response in coronavirus 2019 (COVID-19) can help understand the pathogenesis of this disease. The aim of the study was to assess the usefulness of new neutrophil activation parameters: Immature Granulocyte (IG), Neutrophil Reactivity Intensity (NEUT-RI), Neutrophil Granularity Intensity (NEUT-GI), and data relating to granularity, activity, and neutrophil volume (NE-WX, NE-WY, NE-WZ) available in hematology analyzers to distinguish convalescent patients from patients with active SARS-CoV-2 infection and healthy controls (HC). The study group consisted of 79 patients with a confirmed positive RT-PCR test for SARS-CoV2 infection, 71 convalescent patients, and 20 HC. We observed leukopenia with neutrophilia in patients with active infection compared to convalescents and HC. The IG median absolute count was higher in convalescent patients than in COVID-19 and HC (respectively, 0.08 vs. 0.03 vs. 0.02, p < 0.0001). The value of the NEUT-RI parameter was the highest in HC and the lowest in convalescents (48.3 vs. 43.7, p < 0.0001). We observed the highest proportion of NE-WX, NE-WY, and NE-WZ parameters in HC, without differences between the COVID-19 and convalescent groups. New neutrophil parameters can be useful tools to assess neutrophils’ activity and functionalities in the immune response during infection and recovery from COVID-19 disease.

Immune profiling of COVID-19: preliminary findings and implications for the pandemic

SARS-CoV-2 infection can have widely diverse clinical outcomes, from asymptomatic infection to death, with many possible clinical symptoms and syndromes. It is thus essential to understand how the virus interacts with the host immune system to bring about these varied outcomes and to inform vaccine development. We now know that both antibody and T cell responses are induced in the majority of infected individuals, and that cross-reactive responses from other coronaviruses also exist in the uninfected population. Innate immune responses are a key focus of research and may influence the course of disease and the character of subsequent adaptive responses. Finally, baseline immune profiles and changes during early acute infection may be key to predicting the course of disease. Understanding all these aspects can help to create better immune monitoring tools for COVID-19, including tools for predicting disease severity or specific sequelae, perhaps even prior to infection.

Cytokines and Leukocytes Subpopulations Profile in SARS-CoV-2 Patients Depending on the CT Score Severity

The role of the adaptive microenvironment components in severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection is widely researched, but remains unclear. Studying the common dynamics of adaptive immune response changes can help understand the pathogenesis of coronavirus disease 2019 (COVID-19), especially in critical patients. The aim of the present study was to determine the cytokines concentration and leukocyte subpopulations profiles in the severe COVID-19 (n = 23) and critical (n = 18) COVID-19 group distinguished by the computed tomography (CT) severity score. We observed lower percentage of lymphocyte subpopulation, higher neutrophils to lymphocytes ratio (NLR) and higher IL-6 concentration in critical COVID-19 group than in severe group. CT severity score was negative correlated with proportion of lymphocytes, lymphocytes T, CD4+ cells, Treg cells and NK cells and positive correlated with neutrophils, NLR, and IL-6. In critical group more correlations between cytokines and lymphocytes were observed, mainly between TNF-α, IL-1β and lymphocyte subpopulations. The collective assessment of the cytokine profile, leukocyte subpopulations and the CT severity score can help to characterize and differentiate patient in advanced COVID-19 than the study of single parameters. We have shown that the interconnection of elements of the adaptive microenvironment can play an important role in critical COVID-19 cases.