Bosting the immune system to help destroy cancer cells

Research on mice has enabled scientists to identify a new protein that increases the number of cells in the immune system which are responsible for fighting infections and destroying cancer cells.

Our immune system has a very important job in trying to fight off infections and kill abnormal cells that have become cancerous. The type of cells responsible for doing this are called T cells and they are a type of white blood cells. There are different types of T cells and the ones that can destroy cancer cells are called CD8 T cells (also called killer T cells or cytotoxic T cells). When cancer develops, the cancer cells keep dividing and creating more cancer cells so the CD8 T cells in our immune system have to work very hard to try and stop the cancer cells growing and spreading. However, we know that the CD8 T cells can’t always get rid of cancer cells even if we give chemotherapy and other cancer treatments to help the body with this process. Somehow, the body’s immune system can’t seem to handle it if the CD8 T cells have too much to deal with and cancer cells are then allowed to keep dividing when they should have been stopped or killed off by the immune system.

In the study that we talk about here, researchers wanted to find out if it was possible to increase the number of these ‘killer cells’ and also if they could find a way to help the ‘memory’ of the ‘killer cells’ so that they would more easily recognise the type of cells that they are meant to destroy, such as cancer cells. The research was done on mice because it wouldn’t be safe to do it on humans unless we know more about how it all works.

So what the researchers did was injecting a virus into a group of normal mice and also into a group of mice with genetic mutations (genetic changes). Then they compared the mice that had genetic mutations with normal mice and discovered that a particular group of mutated mice (called Retro mutant mice) produced 10 times as many killer T cells compared to normal mice. This group of mice was much better at fighting the virus infection they had been given and they were also more resistant to a type of skin cancer called melanoma which had also been given to the mice.

The researchers obviously wanted to find out why this happened and when they looked at what was different in the Retro mutant mice, they discovered that these had a high level of a protein that had never been known before. The researchers named the protein LEM (lymphocyte expansion molecule). After this exciting discovery, the researcher also did some laboratory tests that showed that the LEM protein could also help produce more human T cells as well as the T cells in mice.

This may all sound a bit complicated but basically the research has provided new knowledge that scientists can build upon in their search for new treatments for cancer. So it’s very encouraging when things like this happen but it’s important to remember that the research has so far only been done with mice and the only cancer that was studied was the skin cancer called melanoma. Also, although the Retro mutated mice were much better at fighting the virus infection and the melanoma cancer, all of them actually died after two weeks. The researchers thought that the very high activity level in the immune system due to the high number of killer T cells had damaged the blood vessels so badly that the mice died from that but not from the infection or the cancer. This shows very clearly why it is important to do research in laboratories before research is done on humans.

So a lot more research has to be done to see if it’s possible to develop a new and safe cancer treatment that can stimulate and increase people’s killer T cells with the help of the newly discovered LEM protein. First researchers have to do more laboratory research but they hope that they will be able to start studies on humans in about 3 years’ time.

This research was lead by scientists from Imperial College London but carried out by researchers in several countries. You can read more about the study from Imperial College London’s press release and from a report by NHS Choices Health News.

This article was first published : 21.4.2015