T cell responses in patients with COVID-19

Abstract

The role of T cells in the resolution or exacerbation of COVID-19, as well as their potential to provide long-term protection from reinfection with SARS-CoV-2, remains debated. Nevertheless, recent studies have highlighted various aspects of T cell responses to SARS-CoV-2 infection that are starting to enable some general concepts to emerge.

Fig. 1. Potential model of T cell responses during COVID-19 progression.

A proposed model of CD8⁺ T cell responses (a) and CD4⁺ T cell responses (b) during COVID-19 progression in mild versus severe disease. Tables show the immune parameters that have been reported to differ between mild and severe COVID-19. Phenotype data are collated from the references cited in this Progress article. Results that have been confirmed by multiple studies are indicated in bold type. CCL, CC-chemokine ligand; CCR6, CC-chemokine receptor 6; CTLA4, cytotoxic T lymphocyte antigen 4; CX3CR1, CX3C-chemokine receptor 1; CXCL, CXC-chemokine ligand; GZMB, granzyme B; ICOS, inducible co-stimulator; IFNγ, interferon-γ; KLR, killer cell lectin-like receptor; LAG3, lymphocyte activation gene 3; TCR, T cell receptor; T_FH cell, T follicular helper cell; T_H1 cell, T helper 1 cell; T_H2 cell, T helper 2 cell; T_H17 cell, T helper 17 cell; TIGIT, T cell immunoreceptor with immunoglobulin and ITIM domains; TIM3, T cell immunoglobulin and mucin domain-containing protein 3; TNF, tumour necrosis factor; T_reg cell, regulatory T cell.