Immune Respose

• Primary response

  • First exposure to an antigen
  • IgM is the dominant antibody
  • 10 -17 days until max response
  • Symptoms obvious
• Secondary response

  • Second exposure to an antigen
  • IgG is dominant antibody → more stable and greater affinity for antigen
  • 2 – 7 for maximum response
  • Symptoms mild or absent
• It may be several days or weeks before the immune system destroys the Pathogens during this time, the pathogens will multiply and many will produce toxins - the cell damage that they cause and the toxins released can make a person feel very ill
• You probably do not even realise that you have been re-infected and do not suffer from any symptoms (you are immune)
• When a new pathogen enters the body for the first time, there will be only a few lymphocytes with complementary antibodies in their plasma membranes; for primary response to be effective, it needs time for clonal selection, clonal activation, lymphocyte differentiation of B and T cells, plasma B cells to produce sufficient antibodies and T killer cells to destroy all pathogen-containing cells
• However, the primary immune response leaves many more specific memory cells (both B cells and T cells) stored in the lymph nodes
• Secondary immune response occurs if the same pathogen infects the body again, since the body has many specific B and T memory cells, it is much faster and more effective; more antibodies are released quicker, and remain in the circulation longer