IMMUNOTHERAPY: CANCER TREATMENT
Immunotherapy is a treatment that uses the body’s immune system to combat cancer. It consists of stimulating the immune system to do what it does effectively. Some of this therapy is still in clinical trials.
The immune system is a network of cells and organs that work together to defend the body against foreign substances (antigens, pathogens) such as bacteria, viruses, and cancer cells. When the body discovers an antigen, several kinds of cells go into what is called an immune response.
Below is a description of some of the cells that are part of the immune system:
Macrophages: Macrophages are the body’s first line of defense and have many roles. They are the first cells to recognize and capture antigens. They break down these substances and present the smaller proteins to the T lymphocytes. (T cells are programmed to recognize antigens). Macrophages also produce substances called cytokines, which help regulate the activity of lymphocytes.
Lymphocytes: Lymphocytes are one of the main types of immune cells. They are divided into B and T cells. B lymphocytes produce antibodies such as proteins (gamma globulins) which recognize antigens and attach themselves to these substances. Each B cell is programmed to make one specific antibody. When a B cell comes across its antigen, it creates large cells known as plasma cells. Each plasma cell is essentially a factory for producing an antibody. An antibody matches an antigen to essentially help facilitate the death of the pathogenic cell. Whenever the antibody and antigen interlock, the antibody marks the antigen for destruction. B cells are powerless to penetrate the cell, so the task of attacking these target cells is left to T lymphocytes.
T lymphocytesare: Cells that are programmed to recognize, respond to, and remember antigens. T cells contribute to the immune defenses in two major ways. Some direct and regulate immune responses. When stimulated by the pathogen presented by the macrophages, the T cells make lymphokines that signal other cells. Other T cells are able to destroy targeted cells directly.
Dendritic cells: Dendritic cells are known as the most efficient antigen-presenting cell type, with the ability to interact with T cells and initiate an immune response. Dendritic cells are receiving increasing scientific and clinical interest because of their role in the immune response and potential use with tumor vaccines. There are currently treatments in Germany which use dendritic cells to treat cancer.
Granulocytes: There are three types of white blood cells known as granulocytes, which are part of the immune response. Neutrophils are the most common white blood cells in the body. An infection increases their numbers. They are the major components of abscesses and are found around common inflammations. Their task is to eat and destroy pathogens. Basophils and eosinophils interact with certain foreign materials. Their increased activity may lead to an allergic reaction.
All of the immune cells work together, and need to communicate with each other. They secrete a large number of special protein molecules, called cytokines, which act on other cells. There are many different cytokines. Examples of these are interleukins, interferons, tumor necrosis factors, and colony-stimulating factors. Some immunotherapy treatments involve giving larger amounts of these proteins by an injection or infusion. This is done to stimulate the cells of the immune system to act more effectively.
KINDS OF IMMUNOTHERAPY:
The following are kinds of immunotherapies that are commonly used in traditional and scientific medical practice.
Biological response modifiers Biological response modifiers are substances that have no direct anti-tumor effect, but are able to trigger the immune system to indirectly affect tumors. These include cytokines such as interferons and interleukins.
Colony-stimulating factors Blood cells are produced in the body’s bone marrow. There are three major types of blood cells: white blood cells, which fight infection; red blood cells, which carry oxygen to and remove waste products from organs and tissues; and platelets, which enable the blood to clot. Colony-stimulating factors are substances that stimulate the production of blood cells. They do not directly affect tumors, but through their role in stimulating blood cells, they can be helpful in supporting the immune system during cancer treatment.
Tumor vaccines Researchers are developing vaccines that may encourage the immune system to recognize cancer cells. These are designed work in a similar way as vaccines for measles, mumps, and smallpox. The difference in cancer treatment is that vaccines are used after someone has cancer. The vaccines would be given to prevent cancer from returning, or to enable the body to reject tumors. The use of tumor vaccines continues to be studied in clinical trials.
Monoclonal antibodies Monoclonal antibodies are laboratory-produced substances that can locate and bind to certain proteins. They do this by reacting against tumor-associated proteins on the surface of certain cells. These antibodies can be used to detect tumors, or as therapy to deliver drugs, toxins, or radioactive material directly to a tumor. Monoclonal antibodies can be given to target particular molecules on the cell surface. Examples of these antibodies are Rituximab to target lymphoma cells and Herceptin to target cells, including breast cancer cells.
SIDE EFFECTS OF TREATMENT
Like other forms of cancer treatment, immunotherapies can cause a number of side effects. These include flu-like symptoms, fever, extreme fatigue, chills, memory loss, neuropathy, nausea, bone pain and loss of appetite. Rashes or swelling may develop at the site where the modifiers are injected.