Study on memory T cells of COVID-19 convalescent patients could power effective vaccine strategies

A group of immunology researchers from KAIST has discovered that a majority of the COVID-19 convalescent patients develop and maintain T cell memory for more than 10 months irrespective of the severity of their symptoms.

Professor Shin (left) and Ph.D. candidate Chung. Image Credit: KAIST.

Moreover, the memory T cells proliferate quickly once they come across cognate antigen and accomplish their multifunctional roles.

The research offers new perceptions for effective vaccine approaches against COVID-19, taking into account the multipotency and self-renewal capacity of memory T cells.

COVID-19 occurs due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Upon recovery, the patients develop SARS-CoV-2-specific adaptive immune memory. The adaptive immune system comprises two main components—T cells that eliminate infected cells and B cells that produce antibodies.

The research findings indicate that the protective immune function of memory T cells would be executed upon re-exposure to SARS-CoV-2.

The role of memory T cells against SARS-CoV-2 garnered attention recently as neutralizing antibodies decrease after recovery. Memory T cells do not prevent the infection itself; however, they play a crucial role in inhibiting the acute progression of COVID-19. But the longevity and functional maintenance of SARS-CoV-2-specific memory T cells are yet to be revealed.

Professor Eui-Cheol Shin along with his associates analyzed the characteristics and functions of stem cell-like memory T cells that play a vital role in long-term immunity. The team used state-of-the-art immunological techniques to determine the generation of stem cell-like memory T cells and multi-cytokine-producing polyfunctional memory T cells.

The disclosure of long-term immunity of COVID-19 convalescent patients serves as an indicator for the long-term persistence of T cell immunity, a significant goal for upcoming vaccine development. The research also helps evaluate the long-term efficacy of existing COVID-19 vaccines.

At present, the researchers are performing a follow-up study for identifying the memory T cell formation and functional characteristics of those who received COVID-19 vaccines. They also intend to gain insights into the immunological effect of COVID-19 vaccines by comparing the characteristics of memory T cells from vaccinated individuals with those of COVID-19 convalescent patients.

The researchers who led the study, Jae Hyung Jung and Dr. Min-Seok Rha, commented, “Our analysis will enhance the understanding of COVID-19 immunity and establish an index for COVID-19 vaccine-induced memory T cells.”

This study is the world’s longest longitudinal study on differentiation and functions of memory T cells among COVID-19 convalescent patients. The research on the temporal dynamics of immune responses has laid the groundwork for building a strategy for next-generation vaccine development.”

Eui-Cheol Shin, Professor, Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology