Tumor-infiltrating lymphocytes are cells that actively attack and destroy the cells that make up a tumor. There are a number of different antibodies that fall into this class of cells, and in order to destroy most tumors, several of them must be present. These lymphocytes are the body's natural defense against cancer and can often completely destroy tumors without the assistance of additional cancer therapies. In patients who must undergo therapy, including radiation or chemotherapy, tumor-infiltrating lymphocytes are still an important factor in recovery.
Several types of tumor-infiltrating lymphocytes exist, and many of them are in a class of white blood cells known a T or killer T cells. T lymphocytes are essential to the destruction of a tumor because they identify a growth as unwanted, begin to destroy it with certain enzymes and trigger other cell's assistance in the destruction of the rest of the tumor. Natural killer cells are also used in the destruction of tumors.
One of the main properties of tumor-infiltrating lymphocytes is that they are cytotoxic. This gives them the ability to kill cells that they come into contact with. Cytotoxic cells are used by the immune system for a variety of different purposes, including the destruction of cells infected with bacteria or viruses and the destruction of cells that have been damaged or that are faulty. Cancerous cells have a fault in that they do not undergo cell division and death at the normal rate. Rather, they divide indefinitely and do not die when conditions become too crowded or when faults appear in their deoxyribonucleic acid (DNA).
By targeting faulty cells, tumor-infiltrating lymphocytes are able to kill off the cells in a cancerous growth. In most cases, these growths are completely destroyed before a patient shows any signs of having cancer. Many growths do, however, expand too quickly for tumor-infiltrating lymphocytes to destroy, and the tumor will need to be treated medically.
Studies have shown that greater concentrations of tumor-infiltrating lymphocytes correspond to an improved chance of survival in cancer patients. Cancer treatments are often not entirely effective and work better when supplemented by an active and healthy immune system. The presence of many tumor-infiltrating lymphocytes around a tumor means that the patient's body is actively attacking the growth and attempting to destroy it. Patients with high concentrations of these cells have a greater chance of going into remission and having no recurrence of the cancer.