One of the body's defenses against deadly cancer cells may have just received a much-needed boost. Researchers at Imperial College London have happened upon a previously unknown protein that ramps up the presence of all-important cytotoxic T cells, which destroy virus-infected and cancerous cells.

The scientists have named their discovery lymphocyte expansion molecule (LEM), which they unearthed while screening mice with genetic mutations. The found that a particular strain of mice was producing 10 times the normal amount of cytotoxic T cells once it had been infected with a virus. The result was an improved ability to contain the virus and a heightened resistance to cancer.

The cause for this boost in immune response, the scientists found, was the huge presence of a particular protein, their new friend LEM. Following this finding, the scientists were able to establish that LEM also regulates the levels of T cells in humans.

These findings could have important implications for the development of anti-cancer therapies. Though the immune system swiftly swings T cells into action once cancer is detected, they are also quickly overwhelmed and unable to spread widely enough to overcome the disease. If the number of T cells can be multiplied, especially if its by a factor of 10, it could bolster the immune systems chances of winning the battle.

Adding to LEM's credentials as a cancer-fighting candidate was the observation that they also boost another type of T cells. This second type are described as memory cells, as they help the immune system to remember which infections have tried to attack the body before and can launch a more rapid defense.

The researchers will now turn their attention to developing a gene therapy whereby immunity would be improved through the higher presence of LEM.

"Next we will test the therapy in mice, make sure it is safe and see if it can be combined with other therapies," says Professor Philip Ashton-Rickardt, who led the study. "If all goes well, we hope to be ready to carry out human trials in about three years."

The research was published in the journal Science.