August 30, 2015

Exposing the immune system

Imaging CoE scientists have successfully imaged the immune response at the cellular level, laying the groundwork for significant medical advances.

For the first time, a group of researchers have been able to visualise how immune cells are activated and work together to fight off a virus infection. The new study, based at the University of Melbourne and co-authored by Imaging CoE scientists, has revealed the interactions involved in priming the immune response. Excitingly, the findings could be used to improve current vaccines, bringing hope to thousands of people at risk of chronic and deadly diseases.

Comprised of a network of organs, cells and tissues, the immune system is incredibly complex. Although many studies have examined how an immune response is initiated, very little is known about the way individual cells in the immune system coordinate themselves to fight off infections. This is because no-one has ever been able to see this phenomenon occurring – until now, that is.

Using highly sophisticated microscope technology, the team imaged the cells of the immune system in real time within the tissues of mice. They made movies of the three major white blood cell players involved in initiating the immune response to Herpes Simplex virus infection – dendritic cells, killer T cells and helper T cells – and observed the intricate interactions that took place.

“We discovered that the immune cells make a series of interactions, like a tag team, with the helper T cells first responding and then assisting the killer T cells,” says the University of Melbourne’s Dr Scott Mueller, co-senior author of the study and an Associate Investigator at the Imaging CoE. “Revealing this dynamic immune cell dance for the first time explains how the immune system can respond so quickly to an infection on the skin.” The study also highlighted a previously unidentified level of control of T cell activation to peripheral infection.

The scientists are now planning to dig more deeply into the mechanisms of the immune system, and explore how helper T cells actually go about delivering their help to killer T cells via dendritic cells. They will also explore how the dynamic interactions they observed in this study affect the immune response as a whole.

By showing us how immune cells behave, and providing an insight into the critical steps required to stimulate immunity, the team’s discovery could lead to a range of useful applications in medicine. “Armed with knowledge of how the immune cells behave, we may be able to improve responses to diseases such as HIV, or alternately disrupt immune cell interactions where they are not wanted, such as during autoimmune diseases,” Mueller says.