Predominance of CD137⁺ And TNF-α Expressing CD8⁺ Central Memory T Cells in Mild COVID-19 Recovered Patients Upon SARS-CoV-2 Re-Exposure

ABSTRACT

Introduction

Memory CD8⁺ T cells are essential for long-term immune protection in viral infections, including COVID-19.

Methods

This study examined the responses of CD8⁺ TEM, TEMRA, and TCM subsets from unvaccinated individuals who had recovered from mild and severe COVID-19 by flow cytometry.

Results and Discussion

The peptides triggered a higher frequency of CD8⁺ TCM cells in the recovered mild group. CD8⁺ TCM and TEM cells showed heterogeneity in CD137 expression between evaluated groups. In addition, a predominance of CD137 expression in naïve CD8⁺ T cells, TCM, and TEM was observed in the mild recovered group when stimulated with peptides. Furthermore, CD8⁺ TCM and TEM cell subsets from mild recovered volunteers had higher TNF-α expression. In contrast, the expression partner of IFN-γ, IL-10, and IL-17 indicated an antiviral signature by CD8⁺ TEMRA cells. These findings underscore the distinct functional capabilities of each memory T cell subset in individuals who have recovered from COVID-19 upon re-exposure to SARS-CoV-2 antigens.

GRAPHICAL ABSTRACT

KEYWORDS:

• Immunological memory
• Central memory T cells
• effector memory T cells
• effector memory T cells
• SARS-CoV-2 infection
• COVID-19

Acknowledgments

The authors are grateful to all volunteers who, despite their difficulties, agreed to participate in our research and all professionals working tirelessly to end the COVID-19 pandemic.The authors are also grateful for the Conselho Nacional de Desenvolvimento Científico e Tecnológico- CNPq (Number 440939/2020-8) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior- CAPES fellowship support (88887.506771/2020-00) for the financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Conceptualization, T.S.L.K., F.S.A., and B.C.G. experiment design and performance, P.H.S.P.,F.S.A., B.G.C., I.A.M., F. L. A. A. A.,R.C.V.,D.J.; writing – original draft preparation, L.H.A.C.-S., A.G.A. and F.S.A.; writing – review, editing and supervision, T.S.L.K and I.P.G.A. All authors have read and agreed to the published version of the manuscript.

Ethics statement

All experiments complied with relevant regulations, institutional guidelines, and ethical standards of the Declaration of Helsinki. Informed consent was obtained from all enrolled volunteers. This study was approved by the National Commission of Research Ethics (certificate CAAE: 31354720.0.0000.5188).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/08820139.2024.2376003.