Immunotherapy, also called biologic therapy, is a kind of treatment which suppresses (suppression immunotherapy) or boosts (activation immunotherapies) the immune system. Suppression immunotherapies are used to treat allergies or autoimmune diseases. This makes the highly sensitive immune system not respond to allergens. They are also utilized to prevent organ rejection among organ transplant recipients. On the other hand, activation immunotherapies boost the immune system as in the case of cancer treatments which are used to stop cancer cells from spreading to other body parts.