Immune systems can differentiate an unknown substance when it enters the body because the molecules in the antigen area are different from those found in the body.
The immune system uses a variety of techniques to fight off a criminal, one of the most important being the building up of the immune system.
B lymphocytes (or B cells) are specialized white blood cells that produce antibodies.
When an antigen attaches itself to the surface of a B cell, it causes the cell to multiply and mature into a clone, which is a group of identical cells.
Millions of antibodies are released into the bloodstream and the lymphatic system by mature B cells, known as plasma cells.