Cancer cells are normal healthy cells that lose the natural ability to regulate their growth and division. The immune system fails to recognize cancer cells as foreign bodies and does not attack. Specific naturally produced proteins can boost the action of the immune system and mark cancer cells for destruction.
What Are Cytokines?
Immune cells produce a specific type of protein called cytokines. Cytokines act together in cascades to enhance or suppress the immune system. The proteins directly attack foreign bodies or infected or damaged cells, or they signal other immune system cells to attack. The body naturally produces cytokines, or they are manufactured. Laboratory produced cytokines are referred to as biological response modifiers, according to the National Cancer Institute (NCI).
Types of Cytokines
A number of different types of cytokines have been identified, each with unique actions. Classes of cytokines include interferons, interleukins, colony-stimulating factors (CSFs) and monoclonal antibodies, according to the NCI. Vaccines, gene therapies and other agents that modify the immune system also rely on cytokines.
Activity Against Cancer
Cytokines fight or control cancer in a number of ways, according to the NCI. They interrupt the pathways that contribute to the uncontrolled growth of cancer cells and prevent cancer from metastasizing to other organs. Cytokines bind to cancer cells, making them easily recognizable and more susceptible to the action of other immune cells. Other cytokines enhance the killing action of immune cells and help the natural ability of the body to repair cells damaged by radiation or chemotherapy.
Cytokines for Cancer Treatment
Interferon-alfa (INF-a), interleukin-2 (IL-2) and CSFs have shown promise as cancer therapies. INF-a slows the growth of cancer cells, and promotes more normal cell activity and stimulates the body's natural immune system to fight cancer cells, according to the NCI. The Food and Drug Administration has approved INF-a for the treatment of melanoma, chronic myeloid leukemia, AIDS-related Kaposi's sarcoma and hairy cell leukemia. It is also being studied for treating kidney cancer and non-Hodgkin's lymphoma. IL-2 acts indirectly on cancer cells by stimulating lymphocytes to kill cancer cells. IL-2 is approved for treating metastatic kidney cancer and metastatic melanoma and is being investigated for leukemia, lymphoma and cancers of the brain, colon, breast and prostate. CSFs have no effect on cancer cells. Instead, these agents stimulate bone marrow to produce blood cells. Cancer therapies typically damage white and red blood cells and platelets, causing anemia and increasing the patient's risk for infection. By stimulating the production of all types of blood cells, CSFs help patients tolerate higher doses of chemotherapy.
Side Effects
Cytokines are naturally occurring proteins, but they still may cause side effects. Adverse effects vary among agents and patients. The most common side effects are reactions at the injection site and flu-like symptoms, such as fever, chills, fatigue, nausea and vomiting. INF-a may cause depression and decreased energy. IL-2 may cause capillary leak syndrome, and higher doses may result in low blood pressure, blood and kidney toxicities and pulmonary edema.
Tags: immune system, cancer cells, cancer cells, blood cells, action immune