Unit 4 - Immunology and Public Health

Unit 4 – Immunology and Public Health 1. The Immune System 2. Infectious Diseases and immunity Non-specific defences Specific cellular defences Transmission and control Active Immunisation and Vaccination and the evasion of immune responses

By the end of this section you will be able to ….. 1. The Immune System b) specific cellular defences By the end of this section you will be able to ….. describe what is meant by immunological memory state the benefits of having memory cells.

From primary to secondary 

Primary response When a pathogen infects the body, it takes time to raise an immune response and select the correct T and B cells (clonal selection) and produce antibodies. This is called the primary response, and very often it is too slow to prevent the pathogen causing illness.

Secondary response However, if the person survives, and they come across the SAME pathogen a second time, they will have a much different secondary response! This is because the body has created MEMORY CELLS Some of the T and B lymphocytes that were produced by clonal selection after the first exposure survive long term as MEMORY CELLS. When the SAME foreign antigen is recognised by these memory cells a second time, they very quickly form many clones of both T cells and antibody-producing B cells. This means that their are more antibodies produced faster and for a longer duration. This is the secondary response.

Can you now …. describe what is meant by immunological memory state the benefits of having memory cells.