These three terms are a broad category which involve treatment with agents derived from biologic sources, or which provoke the biologic response in humans. The immune system relies upon the antigen-antibody response. During this description, think of a battle.
Antigens can be germs, viruses, pollens, or even cells from another person.
Cancer cells have antigens which are not found on normal cells. Our bodies see these antigens as abnormal and produce antibodies specific to those antigens. Antibodies are like buglers calling the soldiers to attack. Remember, specific antibodies only fight their matching , or targeted, antigens. They are also considered to be most effective when the body's own immune system is at its peak, such as immediately after diagnosis, first surgery, or just after the first indication of recurrence.