The use of immune-based reagents such as T cells and antibodies for therapeutic purposes, or the use of methods that will modify a patient’s immune system to better fight disease. Under normal circumstances the immune system will eradicate an infectious agent using antibodies and T cells as its main weapons. The immune system is also capable of recognizing and eradicating certain cancers. When this does not occur, disease-specific antibodies or T cells can be isolated and introduced into a patient to enhance the patients’ immune response. In other cases, an aberrant immune response can lead to an attack on self-tissue and cause a “autoimmune disease”, such as diabetes. Here, immunotherapy may be used to switch off this damaging immune response, using antibodies or proteins such as cytokines that are known to affect the immune process. An over-reactive immune system is also the cause of allergies, where a harmless agent (such as pollen) can lead to an unnecessary immune response. Here again, antibodies, proteins or drugs can be used to modify this immune response