In order to have room for all the cells needed to match millions of possible enemies, the immune system stores just a few of each kind. When an antigen appears, those few matching cells multiply into a full- scale army. After their job is done, they fade away. Lymphocytes Lymphocytes are one of the main types of immune cells. And B cells and T cells are the main types of lymphocytes.
Antibodies ambush antigens circulating in the bloodstream.
However, they are powerless to penetrate cells. Each B cell is prorammed to make one specific antibody. For example, one B cells will make an antibody that blocks a virus that causes the common cold, while another produces an antibody that attacks a bacterium that causes pneumonia. When a B cell encounters its triggering antigen, it gives rise to many large cells known as plasma cells. Every plasma cell is essentially a factory for producing antibody.