Broad phenotypic alterations and potential dysfunctions of lymphocytes in COVID-19 recovered individuals
immunology/immunity
Authors: Yang, et al., 2020
Journal/ Pre-Print: MedRxiv
Tags: Immunology/Immunity
Research Highlights
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Selective lymphopenia of CD4+ T cells in COVID-19 recovered individuals compared to healthy donors.
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Alterations in subset make up of both CD8+ and CD4+ T cells of COVID-19 recovered individuals compared to healthy donors.
Summary
This study examines phenotypic alterations in lymphocytes of 55 COVID-19 recovered patients compared to 55 age matched healthy donors. With respect to overall frequency, CD8+ T cells and B cells were comparable, yet there was a significant decrease in CD4+ T cells in the recovered cohort. Interestingly, there were subset variations amongst CD8+ and CD4+ cells. This study is limited in that patients only donated one sample and therefore changes over time were not observed. Furthermore, there was a lack of analysis of functional variation of the different populations across the cohorts.
Impact for SARS-CoV2/COVID19 research efforts
Understand the immune response to SARS-CoV2/COVID19
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Further strengthens the argument that there is an aberrant T cell response to SARS-CoV-2 infection relative to healthy donors.
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This is particularly highlighted in the reduced number of Tcm cells in recovered patients compared to healthy donors.
Study Type
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Clinical Cohort study
Strengths and limitations of the paper
Novelty:
Standing in the field:Adds weight to the growing opinion that there is an aberrant lymphocyte response, particularly that of T cells, in response to SARS-CoV-2 infection.
Appropriate statistics: T-test used throughout despite no evidence that data sets are normally distributed. Some plots, particularly those in Fig 2, clearly show a skewed data set and therefore a non-parametric test would be more appropriate.
Viral model used:Patients who had recovered from SARS-CoV-2 infection.
Translatability:n/a
Main limitations:
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Co-morbidities of recovered patients not shown, therefore donors may not be matched in this regard.
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This study solely examined surface markers, or the expression of cytokines in a binary way. Single-cell gene expression studies of lymphocytes are likely to be more fruitful in examining how the phenotypic changes seen in lymphocytes of COVID-19 patients pertains to aberrant function.
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Poor statistics
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Very heterogeneous responses within groups indicating that larger group sizes are needed to detect true significance. Also unclear what the biological significance is of some of the differences
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Only percentages of populations shown, would have been useful to see absolute cell counts