Your immune system is made up of various organs, special cells and substances within your body that help to protect you from infections and other diseases.
These organs, cells and substances can do this as they are able to recognise cells and substances that are normally found in your body and cells and substances that are not, such as tumour cells.
The immune system cells travel round your body seeking out any disease-causing organisms or substances or anything new that they don't recognise. If they come across something, your immune system 'raises an alarm' and attacks the unknown substance. These 'foreign' substances are often referred to as 'antigens'. The immune response can also destroy anything containing the foreign substance, such as tumour cells or germs.
When the foreign antigens are detected, special immune cells called B-cells are triggered to produce a substance that attaches to the antigen. These substances are special proteins called antibodies.
Although the antibodies find and attach to the antigens, they can't kill them. This is left to another type of cell, called a T-cell, that are called into kill the foreign cell by giving it a lethal burst of chemicals.
Finally another type of immune cell, called a phagocyte, swallows and eats the destroyed antigen or cell containing the antigen.
Our brains and central nervous system (nerves) are separated from the body's immune system by the blood-brain barrier. However, they have their own immune system called the 'neuroimmune' system that protects them from infection and foreign cells.
If we imagine that tumour cells are like weeds, a gardener (B-cell) would walk around the garden (body) attaching a label (antibody) to every plant that they recognised as a weed (foreign antigen).
The label itself does not kill the weed, but it shows the gardener's assistant (T-cell) which plants they should give a lethal spray of weed-killer to.
The gardening apprentice (phagocyte) then comes round and pulls up all the dead weeds to get rid of them from the garden.
(The gardener specialises in recognising one type of weed only, so there are teams of gardeners to make sure each type of weed is recognised and labelled.)
Researchers are excited about the possibility of using our body's own immune systems to help fight cancer and other tumours. To be able to use the body's natural defenses against tumours has some potential advantages over current conventional treatments.
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