The Immune response:
The immune response is a specific response to the detection of pathogens in the body. It involves B lymphocytes (B cells) and T Lymphocytes (T cells). These are white blood cells with a large nucleus and specialised receptors on their plasma membrane. The immune response produces antibodies. It is the antibodies that actually neutralise the foreign antigens. The immune response also provides long term protection from disease. It produces immunological memory through the release of memory cells which circulate in the body for a number of years.
Starting the response:
An invading pathogen has foreign antigens. In order to trigger the immune response these must be detected by specific T lymphocytes and b lymphocytes. These lymphocytes carry the correct receptor molecules on their membranes. The receptor molecules are cell surface proteins that have a shape that is complimentary to the shape of the antigen. Once the correct T or B lymphocytes detect the antigens, the immune response can begin.
However, there may be only one or very few of the correct T and B lymphocytes in the body. It may take some time for them to find the antigens. The presentation of foreign antigens by a number of cells increases the chances that the correct B and T lymphocytes will locate the antigens. Cells that are attacked by the pathogen will display antigens on their surface. …