A longitudinal study of immune cells in severe COVID-19 patients
clinical immunology/immunity
Running title: Monocytes and antigen-specific T-cells in severe COVID-19.
Authors:Payen D et al.
Journal/ Pre-Print:medRxiv
Tags: Clincal, Immunology/Immunity
Research Highlights
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No significant differences in monocyte subset populations over time in severe COVID19 hospitalised patients
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Although a reduction of CD4 and CD8 T cells was observed, the CD4/CD8 T cells ratio remain the same throughout
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SARS-CoV2 specific CD4 T cells were more potent in secreting cytokines (IFNg, TNFa, IL-2) than CD8 T cells after in vitro stimulation.
Summary
A longitudinal study following 15 severe COVID-19 patients, not on immunomodulatory treatment, to assess lymphocyte subsets and their functionality and monocyte phenotyping in serial peripheral blood samples. As previously reported, a decrease in CD4 and CD8 T cells was observed in severe patients, however no disruption of the CD4/CD8 ratio is shown. Isolation of SARS-COv2-specific T cells showed that after in vitro stimulation CD4 T cells were more capable of secreting cytokines (IFNg, TNFa, IL-2) with higher TNFa, IL-2 positive cells. Overall this study lacks a strong correlation/explanation between their observations.
Impact for SARS-CoV2/COVID19 research efforts
Understand the immune response to SARS-CoV2/COVID19
Study Type
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Clinical Cohort study (15 patients followed overtime with blood collections)
Strengths and limitations of the paper
Novelty: The authors assess the functional potential of the cells by looking at expression of multiple cytokines and monocyte populations overtime.
Standing in the field: This study does not add crucial data to the field.
Appropriate statistics: Yes, but small sample size
Viral model used: Severe COVID-19 hospitalized patients (confirmed by RT-PCR)
Translatability: It would be very interesting to deeper phenotype innate and adaptive immune responses overtime in different disease stages in patients. However, the translational implications of the research are limited.
Main limitations:
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Study lacks details of monocyte subsets and their potential roles. Moreover, the study was confined to analyses of peripheral blood and did not look at macrophages.
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Did not show the gating strategy neither the MFI for cytokine production for instance.
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Limited sample size (n=5 patients for cytokine experiments)
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Did not entirely functionally characterise the cells. It would have been valuable if they had phenotyped SARS-Cov2 specific T cells by FACS over time.