T cells are immune cells that fight off disease. The most common type of T cell, known as conventional T cells, maintains different functions, including activation of other T cells and killing pathogens. However, there is a less common type of T cell known as unconventional T cells. These cells regulate conventional T cells and often suppress conventional T cell function. How these cells develop and protect the body from infection and disease is unclear. Dr. Dan Pellicci and colleagues from Murdoch Children’s Research Institute and Federation University Australia reported on unconventional T cell development and their role in the immune system in a recent Science Immunology paper.
The researchers found that these unconventional T cells elicit an immune response. The discovery of an anti-pathogen role in these T cells has been unknown previously. Scientists can target these cells to prevent cancer and highly infectious diseases by understanding their role in immunity.
Dr. Pellicci and colleagues gathered samples from the Melbourne Children’s Heart Tissue Bank, where samples from children sixteen years old or younger who had heart surgery were kept. The researchers looked at the T cells from the thymus, a gland that further develops or matures T cells. After the T cells exit the thymus, they are ready to activate and target or kill infecting pathogens. Through T cell isolation, Dr. Pellicci and colleagues were able to determine the role of Unconventional T cells.
Scientists found that the thymus produced these unconventional T cells for the first time. What is more exciting is that people have large numbers of these cells in their blood and tissues, accumulating as they age. Until this report, how unconventional T cells developed in the body remained unclear. The report outlines how these cells develop over three stages, similar to conventional T cells developing in the thymus. In this process, T cells enter the thymus and differentiate or change into more mature cells and undergo selection in which the T cells are selected based on function and self-tolerance. The cells are then fully equipped to enter the body and fight disease. Upon maturation, the cells leave and enter different tissues, where they come into contact with an infection and become activated to elicit an immune response.
Previous work suggests that unconventional T cells were developed in the liver during embryonic development in the womb, but Pellici and colleagues refute that work in their paper. It was assumed that the thymus did very little after we were born, but Pellici argues the organ helps fight invading pathogens and maintain good health.
This report is paradigm-shifting and unlocks new information about unconventional T cells. Pellici and colleagues have discovered they play a major role in fighting infectious diseases and pathogens. In addition, they outline the developmental steps that the cells go through to mature within the thymus. Through this new knowledge of unconventional T cells, scientists can target these cells to improve therapeutic regimens against infectious diseases and cancer.
Paper, Dr. Dan Pellicci, Murdoch Children’s research Institute, Federation University Australia, Science Immunology, Melbourne Children’s Heart Tissue Bank