In-depth phenotyping of human peripheral blood mononuclear cells in convalescent COVID-19 patients following a mild versus severe disease course

  1. Chang-Feng Chu
  2. Florian Sabath
  3. Shan Sun
  4. Ying-Yin Chao
  5. Christina E. Zielinski

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Abstract

Background

Covid-19, the disease caused by infection with SARS-CoV-2, has developed to a pandemic causing more than 239, 000 deaths worldwide as of 6th May according to the World Health Organization (WHO). It presents with a highly variable disease course ranging from a large proportion of asymptomatic cases to severe respiratory failure in 17-29% of cases even in the absence of apparent comorbidities 1, 2 . This implies a diverse host immune response to SARS-CoV-2. The immunological characteristics underlying these divergent disease courses, however, still remain elusive. While insights into abrogations of innate immunity begin to emerge, adaptive immune responses towards SARS-CoV-2 are poorly investigated, although they serve as immune signatures of protection and vaccine responses. We therefore set out to characterize immune signatures of convalescent COVID-19 patients stratified according to their disease severity.

Methods

We performed high-dimensional flow cytometric profiling of peripheral blood mononuclear cells of convalescent COVID-19 patients who we stratified according to their disease severity by a physician-assisted questionnaire based assessment of COVID-19 symptoms.

Results

Surprisingly, we did not observe any difference in the relative proportions of any major immune cell type in convalescent patients presenting with different severity of COVID-19 disease except for a reduction in monocytes. The frequency of T naive T cells was significantly reduced in CD4 + and CD8 + T cells, whereas other T cell differentiations states (T CM , T EM , T EMRA ) remained relatively unaffected by COVID-19 severity as assessed approximately two weeks after infection.

Conclusions

In our COVID-19 patient cohort, which is characterized by absence of comorbidities and therapeutic interventions other than symptomatic antipyretics, the immunophenotype is similar irrespective of a highly variable disease severity. Convalescence is therefore associated with a rather uniform immune signature. Abrogations, which were previously identified in the innate and adaptive immune compartment of COVID-19 patients should be scrutinized for direct associations with a preconditioned immune system shaped and made vulnerable for SARS-CoV-2 by preexisting comorbidities.

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  1. ScreenIT

    SciScore for 10.1101/2020.05.25.20112763: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: Ethical approval was obtained from the Institutional Review Board of the Technical University of Munich (164/20S and 147/20S).
    RandomizationPatient characteristics: Patients were randomly selected based on positive SARS-CoV-2-RNA test results by RT-PCR from throat swab samples as well as absence of co-morbidities or pregnancy as assessed by a physician (lung diseases, cardiovascular diseases, cancer, autoimmune diseases, therapeutic immunosuppression).
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Cell purification flow cytometry: Peripheral blood mononuclear cells (PBMC) were isolated immediately after blood collection into heparinized collection tubes (within 30 min) by density gradient centrifugation using Biocoll Separting Solution (Merck) and analyzed immediately by flow cytometry (BDFortessa) using the following antibodies (CD45RA-BUV737, clone HI100; CD4-BV785, clone RPA-T4; CD25-BV650, clone BC96; CD8-BV510, clone RPA-T8; CD14-PacificBlue, clone HCD14; CD 19-PerCP-Cy5.5, clone HIB19; CD56-FITC, clone MEM-188; CD197-PE-Cy7, clone G043H7; CD127-PE/Dazzle594, clone A019D5; CD3-PE, clone SK7; γδTCR-APC, clone B1), all from Biolegend.
    CD45RA-BUV737
    suggested: None
    Software and Algorithms
    SentencesResources
    Analyses were performed using GraphPad Prism 8.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.05.25.20112763 on medRxiv