The human body makes millions of different types of B cells each day that circulate in the blood and lymphatic system performing the role of immune surveillance. They do not produce antibodiesuntil they become fully activated. Each B cell has a unique receptor protein (referred to as the B cell receptor (BCR)) on its surface that will bind to one particular antigen.
If the pathogens are able to get past the first line of defence, for example, through a cut in your skin, and an infectiondevelops, the second line of defence becomes active. Through a sequence of steps called the immune response, the immune system attacks these pathogens.
The second line of defence is a group of cells, tissues and organs that work together to protect the body. This is the immune system.
T helper cells: These cells are like the bosses. They give instructions to other cells by producing signals. Each T helper cell only looks out for one type of pathogen. Many T helper cells are needed to watch for many different diseases or invaders.
B cells: These produce antibodies, which lock onto the antigen of invading bacteria and immobilise them until the macrophage consumes them. Some B cells become memory cells after being activated by the presence of antigen. These cells are able to live for a long time and can respond quickly following a second exposure to the same