13 May 2011

Researchers Uncover How White Blood Cells Carry Out ‘Triage’ on Injured Tissue

Researchers at the University of Edinburgh, funded by the Medical Research Council (MRC), have unearthed the mechanism behind an entirely new kind of inflammation, showing that white blood cells have an additional, previously unknown way to cope with injury and infection. The discovery of a fundamentally different form of inflammation opens up new opportunities to develop drugs that target this process to aid healing and recovery from infection.

This seminal study, published online today in Science, challenges current scientific thinking on inflammation and repair systems within the body and will not only improve researchers’ understanding of how the body fights infection and injury, but could also shed light on how this system can become corrupted and cause allergies, help tumours to grow and cause scarring.

It was previously assumed that when tissue becomes injured or infected, white blood cells enter the tissue via the bloodstream to repair and protect it from further damage, causing the area to become inflamed. Edinburgh researchers have found that the critical white blood cell in this process is also capable of carrying out a ‘triage’ process locally; rapidly dividing within the tissues to form a protective layer, without relying on white blood cells from the blood stream.

White blood cells known as macrophages, are a crucial component of the body’s inflammatory response and act as the ‘traffic police’ within the immune system. White blood cells work by flooding the infected area, eating up bacteria to fight infection, as well as engulfing debris caused by tissue damage. This process is one of the main weapons in the body’s arsenal against attacks from foreign bodies. However in certain cases, it can cause more problems than it solves. Cells that come in from the blood often cause collateral damage when trying to kill infection. Although this newly discovered form of local inflammation is less likely to cause collateral damage, the researchers have found that it is directly linked to the same processes that cause allergy and scarring.

Professor Judith Allen who led the study says:

“Inflammation is often regarded as a ‘bad thing’ but also has important positive roles within the body. By understanding more about how this local form of inflammation works, we will be able to improve our knowledge of how white blood cells control tissue damage. This could help us to develop new kinds of inflammatory drugs which can benefit patients on several fronts - either to develop drugs which encourage this effect to help the body recover from infection or injury, or to minimise it to prevent allergic reactions or scarring.”

Professor Doreen Cantrell, Chair of the MRC Infection and Immunity Board based at the University of Dundee adds:

“Understanding local inflammatory responses and how they are controlled was a major ‘knowledge gap’ identified by the MRC Strategic Review of Human Immunology back in 2007. Breakthroughs of this nature can only take place with the appropriate support, which is why the MRC invests in strategies to address them and improve the health and outcomes of the millions of patients suffering from immune diseases.”