Cytotoxic T cells are an important component of the immune system, but in the face of serious infections or advanced cancer, they are often unable to proliferate in large enough quantities to fight the disease. Scientists have discovered a new protein known as lymphocyte expansion molecule, or LEM, that promotes the proliferation of cytotoxic T cells, which kill cancer cells and cells infected with viruses. This finding may play a critical role in promoting an individual's immunity to viruses and cancer, thus opening the door to new therapies.
By screening mice with genetic mutations, the research team discovered a strain of mice that produced 10 times as many cytotoxic T cells when infected with a virus compared with normal mice. These mice were able to suppress the infection more effectively, and were more resistant to cancer. They also produced more of a second type of T cells, memory cells, enabling them to recognize infections they have encountered previously and launch a rapid response. The mice with enhanced immunity were found to produce high levels of a hitherto unknown protein, which the researchers named lymphocyte expansion molecule, or LEM.
The researchers further went on to show that LEM modulates the proliferation of human T cells as well as in mice. This discovery was unexpected because the new protein had no known function and does not resemble any other protein. The Imperial research team now aims to develop a gene therapy designed to improve immunity by boosting the production of LEM.
Lead researcher professor Philip Ashton-Rickardt from Imperial College London said, "Cancer cells have ways to suppress T cell activity, helping them to escape the immune system. Genetically engineering T cells to augment their ability to fight cancer has been a goal for some time. By introducing an active version of the LEM gene into the T cells of cancer patients, we hope, we can provide a robust treatment for patients."
The study is published in Science