1. Adaptive Immunity

2. Fourth Line of Defense
Adaptive Immunity: specific immune system that is made up of specialized cells that eliminate pathogens or prevent their growth after exposure
Specific lymphocytes remember the pathogens you have been exposed to and know to respond to them

3. Antigens
Cell -surface protein that tells the body what type of cell it is
Two Types:
Foreign Antigens: antigens introduced from outside the body
Ex: Antigens from bacteria, viruses, etc.
Self-Antigens: antigens produced by the body
Ex: Antigens from tumors signaling their destruction

4. Antibodies
Proteins that bind to bad antigens and lead to their destruction

5. Cells Involved in Adaptive Immunity

6. Lymphocytes Are responsible for adaptive immunity in your body
Two Types:
T Cells: attack infected cells
B Cells: attack pathogens outside cells

7. T Cells Produced in red bone marrow, but mature in the thymus
Responsible for Cell-Mediated Immunity
Cytotoxic T Cells: Kill infected cells by releasing chemicals
Helper T Cells: Activate B cells and Cytotoxic T cells
Memory T Cells: Remember pathogens after exposure

8. B Cells
Originate and mature in red bone marrow; differentiate to fight infection
Plasma Cells: Produce antibodies to attack infection
Memory B Cells: Remember pathogens after exposure

9. Lymphocyte Activation
After Memory B and T cells have been exposed to a pathogen they remain in the lymph nodes until they are exposed to the pathogen again
Then they will activate and start to reproduce
Ex: Strep Throat

10. Lymphocyte Proliferation
Normally the body only has a few lymphocytes that recognize each pathogen, so before they can fight the infection they must reproduce
Two Types:
Proliferation of Helper T Cells: Bind to dendritic cells and reproduce rapidly
Proliferation of Other T Cells and B Cells: Helper T Cells Bind to the lymphocytes that recognized the pathogen and aid in their reproduction and differentiation

11. Antibody-Mediated Immunity
B cells fight pathogens by making and releasing antibodies to attack a specific pathogen
Plasma cells make the antibodies and release them into the bloodstream
Antibodies bind to the antigens of infected cells or free floating pathogens and destroy them
Methods of Destruction:
Antigen Inactivation
Causing antigens to clump together
Activating the complement cascade
Causing the release of chemicals from the immune system
Enhancing phagocytosis
Continues until told to stop by the brain
Memory B cells are stored in the lymph nodes for future use

12. Cell-Mediated Immunity
Caused by Cytotoxic T cells that directly attack pathogens or pathogen infected cells
Release a chemical called perforin which causes infected cells to develop holes in their cell membrane and die

13. How the Immune Response is Stopped
Regulatory T cells signal the immune response to stop