Immunotherapy

The immune system, through a variety of responses working together, protects the body from invading pathogens and eliminates disease. When the body's immune system fails to work properly or is compromised by a chronic or acute disease, the body is unable to keep up with the progression of the disease and needs additional help to fight off debilitating effects.

Providing passive immunity is one of the most widely recognized and used forms of immunotherapy. This process transfers immunity by direct injection of antibodies or antiserum to prevent infectious disease. This provides immediate—though tempo-rary—protection from a specific disease-causing bacteria, virus, or toxin and can also protect persons unable to produce antibodies themselves. These injected antibodies have a short lifespan. No memory cells are created leaving the individual is left susceptible to infection by the same antigen.

Any immunotherapy, whether classified as investigational or approved for use, relies on stimulating the immune response to treat a disease either by increasing the body's own defense mechanisms, injecting specific immunologic proteins, creating abundant T-lymphocytes to destroy infected cells, or genetically altering T-lymphocytes to recognize and destroy cancer cells when reinjected into the body. According to the American Cancer Society, immunotherapy is used to enhance the primary treatment. Immunotherapy relies on activating a portion of the immune system through the use of proteins or medications to improve immune function. An approved use of BCG (an extract of weakened tuberculosis) has been effective in treating bladder cancer by increasing production of T-lym-phocytes. Levamisole is approved as an adjunct to fluorouracil for colon cancer to increase macrophage activity.

The discovery of cytokines, a large diverse group of proteins functioning and released by various cells of the immune system has led to numerous uses of specific cytokines for treating infections, inflammations, autoimmune disorders, and neoplasms. The approved uses of cytokines include interferon–alpha for the treatment of two forms of leukemia, malignant melanoma, and Kaposi's sarcoma; interferon–beta for treating relapsing multiple sclerosis; interferon–gam-ma for treating chronic granulomatous disease; and interleukin–2 for treating metastatic renal cell carcinoma. Research continues into numerous uses of cytokines for immunotherapy.

Other forms of immunotherapy are still being investigated. Gene therapy is being tested as a way to remove melanoma tumors throughout the body. Researchers are experimenting with isolating white blood cells and inserting T-lymphocyte receptors to recognize and destroy cancer. When reinjected into the body, these altered cells seek out and destroy specific cancer cells throughout the body.

Another possible use for immunotherapy is in HIV infection. The HIV virus destroys helper T-lympho-cytes. These cells are important to modulating the immune response. When these cells are destroyed, the entire immune system becomes compromised. T-lymphocytes, the so-called natural killer cells exist in the blood; some have the specificity to seek out and destroy HIV. Theoretically, a patient could have blood drawn, and, in a laboratory environment, have the number of these HIV-specific T-lymphocytes created using a polymerase chain reaction (PCR). These could then be injected back into the patient to assist in fighting disease.

In theory, the purpose of treating the immune system with immune-system components increases the body's ability to fight diseases such as cancer, AIDS, allergies, and autoimmune diseases. In these conditions, the body fails to recognize its own cells and the immune system begins to automatically destroy those cells.

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