Dr Carolien Van de Sandt and Prof Katherine Kedzierska research uncovers old T cells are young at heart

Dr Carolien Van de Sandt, Department of Microbiology and Immunology, first author, and Prof Katherine Kedzierska, Department of Microbiology and Immunology, senior author, were among a group of researchers studying how age shapes our immunity to influenza virus. The pioneering research was published in Nature Immunology, and employed cutting-edge technologies to examine killer T cells in different age groups – newborns, school-aged children, adults and older adults (60+ years).

The world-first discovery revealed special immune cells called ‘killer T cells’ in older adults, directed against influenza viruses, closely resemble those found in newborns and children, but struggle to recognise infected cells – a finding that unlocks the potential for the development of better vaccines and therapies tailored to different age groups.

Killer T cells (also known as CD8+ T cells) play a critical role in the immune system by eliminating virus-infected cells. While much has been studied about these immune cells in adults, little was known about how they evolve and function across the human lifespan – until now.

University of Melbourne’s Dr Carolien van de Sandt, a Senior Research Fellow at the Doherty Institute and first author of the paper, said the team uncovered unexpected similarities in T cell responses between newborns/children and older adults.

“Based on previous studies, we expected to find that killer T cells in older adults were less effective because they had become exhausted or ‘fallen asleep’," said Dr van de Sandt.

“However, to our surprise, the very efficient killer T cells that we detected in children and adults seemed to actually disappear and be replaced with suboptimal cells in older adults. It is almost as if you replace the sword of a Roman soldier with a kitchen knife; they can learn how to use it, but it will never be as efficient as the sword.

One of the most intriguing findings of the study was that these cells, with a lower ability to recognise influenza viruses, displayed gene features closely similar to T cells found in newborns.

University of Melbourne’s Professor Katherine Kedzierska, Head of the Human T cell Laboratory at the Doherty Institute and senior author on the paper, said this research greatly contributes to our understanding of how immunity changes over an individual’s lifespan, and has the potential to significantly advance the field of vaccinology.

“Our findings suggest that if we want to boost killer T cells through vaccination, the timing may play an essential role to maintain these optimal killer T cells into old age,” said Professor Kedzierska.

This study is a turning point for the research into ageing immunity. It has far-reaching implications and opens up new possibilities for the development of better vaccines and therapies tailored to different age groups.

This article was originally published on 26 September 2023 by the Peter Doherty Institute for Infection & Immunity.

The Doherty Institute is a joint venture between The University of Melbourne and The Royal Melbourne Hospital.