Find out what the function of memory cells is.

Principles of Immunology

Definitions of antigen and antibody

Antigen: A molecule that triggers an immune response.

Antibody: A molecule secreted in response to a specific antibody.

There are a number of types of white blood cell. Those involves in specific immune responses are called lymphocytes . There are two types of lymphocytes.

T-lymphocytes are involved in a cellular response. They include some cells which attack and destroy the bodies own cells that have viruses reproducing inside them. They also include T-helper cells which are needed if B-lymphocytes are to respond to an infection.

B-lymphocytes are involved in the humoral response. This involves the the production of antibodies. B-lymphocytes develop in the bone marrow. They develop into very large numbers of cells each with a different antigen receptor on its surface. Each of these is capable of producing a specific antibody to that antigen. When stimulated by a T-helper cell the B-lymphocytes with a specific antigen receptor start to divide and form a clone of identical cells. This is known as clonal expansion.

Of the cells in this clone some become plasma cells and actively produce large quantities of antibody. Others become long lived memory cells.