EVERYDAY SCIENCE

Detailed explanation-1: -The immune system has a vital role: It protects your body from harmful substances, germs and cell changes that could make you ill. It is made up of various organs, cells and proteins.

Detailed explanation-2: -The immune system recognizes invaders by their antigens, which are proteins on the surface of the invading cells (see Figure 1). Every cell or substance has its own specific antigens, and a person’s cells carry “self-antigens” that are unique to that individual.

Detailed explanation-3: -The immune system can clearly recognize cancer cells as different, yet often it is unable to stop them from growing. Scientists are trying to understand why.

Detailed explanation-4: -Some cells of the immune system can recognise cancer cells as abnormal and kill them. But this may not be enough to get rid of a cancer altogether. Some treatments aim to use the immune system to fight cancer.

Detailed explanation-5: -That is, the immune system must be able to distinguish what is nonself (foreign) from what is self. The immune system can make this distinction because all cells have identification molecules (antigens) on their surface. Microorganisms are recognized because the identification molecules on their surface are foreign.