ABSTRACT
Blood cell analysis is a major pillar of biomedical research and healthcare. These analyses are performed in central laboratories. Rapid shipment from collection site to the central laboratories is currently needed because cells and biomarkers degrade rapidly. The dried blood spot from a fingerstick allows the preservation of cellular molecules for months but entire cells are never recovered. Here leucocyte elution is optimized from dried blood spots. Flow cytometry and mRNA expression profiling are used to analyze the recovered cells. 50-70% of the leucocytes that are dried on a polyester solid support via elution after shaking the support with buffer are recovered. While red blood cells lyse upon drying, it is found that the majority of leucocytes are preserved. Leucocytes have an altered structure that is improved by adding fixative in the elution buffer. Leucocytes are permeabilized, allowing an easy staining of all cellular compartments. Common immunophenotyping and mRNAs are preserved. The ability of a new biomarker (CD169) to discriminate between patients with and without Severe Acute Respiratory Syndrome induced by Coronavirus 2 (SARS-CoV-2) infections is also preserved. Leucocytes from blood can be dried, shipped, and/or stored for at least 1 month, then recovered for a wide variety of analyses, potentially facilitating biomedical applications worldwide.
Subject(s)
Communicable Diseases/diagnosis , Diagnostic Tests, Routine/methods , Dried Blood Spot Testing/methods , Hematology/methods , Immunophenotyping/methods , Antibodies, Viral/blood , Biomarkers/blood , Blood Specimen Collection/methods , COVID-19/diagnosis , Cell Separation/methods , Communicable Diseases/virology , Erythrocytes/virology , Flow Cytometry/methods , Humans , Leukocytes/virology , RNA, Messenger/blood , SARS-CoV-2/geneticsABSTRACT
The identification of a bacterial, viral, or even noninfectious cause is essential in the management of febrile syndrome in the emergency department (ED), especially in epidemic contexts such as flu or CoVID-19. The aim was to assess discriminative performances of two biomarkers, CD64 on neutrophils (nCD64) and CD169 on monocytes (mCD169), using a new flow cytometry procedure, in patients presenting with fever to the ED during epidemics. Eighty five adult patients presenting with potential infection were included during the 2019 flu season in the ED of La Timone Hospital. They were divided into four diagnostic outcomes according to their clinical records: no-infection, bacterial infection, viral infection and co-infection. Seventy six patients with confirmed SARS-CoV-2 infection were also compared to 48 healthy volunteers. For the first cohort, 38 (45%) patients were diagnosed with bacterial infections, 11 (13%) with viral infections and 29 (34%) with co-infections. mCD169 was elevated in patients with viral infections, with a majority of Flu A virus or Respiratory Syncytial Virus, while nCD64 was elevated in subjects with bacterial infections, with a majority of Streptococcus pneumoniae and Escherichia coli. nCD64 and mCD169 showed 90% and 80% sensitivity, and 78% and 91% specificity, respectively, for identifying patients with bacterial or viral infections. When studied in a second cohort, mCD169 was elevated in 95% of patients with SARS-CoV-2 infections and remained at normal level in 100% of healthy volunteers. nCD64 and mCD169 have potential for accurately distinguishing bacterial and acute viral infections. Combined in an easy and rapid flow cytometry procedure, they constitute a potential improvement for infection management in the ED, and could even help for triage of patients during emerging epidemics.
Subject(s)
Bacterial Infections/diagnosis , COVID-19/diagnosis , Emergency Service, Hospital , Flow Cytometry , Monocytes/immunology , Receptors, IgG/blood , Sialic Acid Binding Ig-like Lectin 1/blood , Adult , Aged , Bacterial Infections/blood , Bacterial Infections/immunology , Bacterial Infections/microbiology , Biomarkers/blood , COVID-19/blood , COVID-19/immunology , COVID-19/virology , Diagnosis, Differential , Female , Host-Pathogen Interactions , Humans , Male , Middle Aged , Monocytes/microbiology , Monocytes/virology , Predictive Value of Tests , Prospective Studies , Reproducibility of ResultsABSTRACT
PURPOSE: The relationship between lung ultrasound (LUS) and chest computed tomography (CT) scans in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia is not clearly defined. The primary objective of our study was to assess the performance of LUS in determining severity of SARS-CoV-2 pneumonia compared with chest CT scan. Secondary objectives were to test the association between LUS score and location of the patient, use of mechanical ventilation, and the pulse oximetry (SpO2)/fractional inspired oxygen (FiO2) ratio. METHODS: A multicentre observational study was performed between 15 March and 20 April 2020. Patients in the Emergency Department (ED) or Intensive Care Unit (ICU) with acute dyspnoea who were PCR positive for SARS-CoV-2, and who had LUS and chest CT performed within a 24-h period, were included. RESULTS: One hundred patients were included. LUS score was significantly associated with pneumonia severity assessed by chest CT and clinical features. The AUC of the ROC curve of the relationship of LUS versus chest CT for the assessment of severe SARS-CoV-2 pneumonia was 0.78 (CI 95% 0.68-0.87; p < 0.0001). A high LUS score was associated with the use of mechanical ventilation, and with a SpO2/FiO2 ratio below 357. CONCLUSION: In known SARS-CoV-2 pneumonia patients, the LUS score was predictive of pneumonia severity as assessed by a chest CT scan and clinical features. Within the limitations inherent to our study design, LUS can be used to assess SARS-CoV-2 pneumonia severity.