Abstract COVID-19 is characterized by profound lymphopenia in the peripheral blood, and the remaining T cells display altered phenotypes, characterized by a spectrum of activation and exhaustion. However, antigen-specific T cell responses are emerging as a crucial mechanism for both clearance of the virus and as the most likely route to long-lasting immune memory that would protect against re-infection. Therefore, T cell responses are also of considerable interest in vaccine development. Furthermore, persistent alterations in T cell subset composition and function post-infection have important implications for patients’ long-term immune function. In this review, we examine T cell phenotypes, including those of innate T cells, in both peripheral blood and lungs, and consider how key markers of activation and exhaustion correlate with, and may be able to predict, disease severity. We focus on SARS-CoV-2-specific T cells to elucidate markers that may indicate formation of antigen-specific T cell memory. We also examine peripheral T cell phenotypes in recovery and the likelihood of long-lasting immune disruption. Finally, we discuss T cell phenotypes in the lung as important drivers of both virus clearance and tissue damage. As our knowledge of the adaptive immune response to COVID-19 rapidly evolves, it has become clear that while some areas of the T cell response have been investigated in some detail, others, such as the T cell response in children remain largely unexplored. Therefore, this review will also highlight areas where T cell phenotypes require urgent characterisation.
【저자키워드】 COVID-19, T cells, lung, Peripheral blood, antigen-specific, Phenotypes, 【초록키워드】 Vaccine development, knowledge, children, disease severity, virus, immune, lymphopenia, T cell, Lungs, Re-infection, immune function, immune memory, Adaptive immune response, predict, mechanism, T cell response, marker, Post-infection, Activation, tissue damage, virus clearance, alteration, characterisation, T cell phenotype, T cell memory, clearance, implication, likelihood, highlight, PROTECT, investigated, characterized, long-lasting, T cell subset, driver, markers of activation, SARS-CoV-2-specific T cell, 【제목키워드】 T cell phenotype,