Chapter 17: Basic Principles Of Adaptive Immunity And Immunization Flashcards
Acquired defenses
Require exposure to an antigen to be activated
Actively acquired
Body makes it’s own antibodies
- take longer to get started, provide long lasting protection
Passively acquired
Give ready made antibodies that came from another source
- immediate but short lived protection
Active natural
Exposure to infectious agent
- ex: bacteria or virus
Active artificial
Vaccine, weakened or killed pathogen
Passive natural
Maternal antibodies through childbirth or breast milk
Passive artificial
Injecting antibodies into someone from another source
- ex: antisera to cure venom from snake bites
Antigen
Antibody generating molecule
- a substance (protein/pathogen) that the body sees as foreign and mounts an immune response against
Epitope
Antigenic determinant
- site on antigen where antibodies bind
Hapten
Small molecule that can serve as an antigen when combined with a large protein and trigger an immune response
Humoral immunity
- Carried out by antibodies circulating in blood
- most effective against antigens outside of body cells
- B lymphocytes originate in bone marrow and mature there
- create antibodies
Humoral immunity mechanism
- B cell recognizes and binds to a specific antigen
- B cell is activated or sensitized
- B cell divides (proliferates into many clones) into plasma cells and B memory cells
- Plasma cells make antibodies specific for original antigen
- antibodies bind to antigen and mark it for destruction
Cell mediated immunity
- occurs at the cellular level
- most effective against antigens that have entered body cells (virus infected, or abnormal/cancer cells)
- T lymphocytes differentiate in thymus
General properties of immune responses
- self vs no self
- specificity
- diversity
- memory
Self vs nonself
The ability to recognize normal host substances as self and foreign substances as nonself
- Developed early in development
- colonial deletion: destroys lymphocytes that recognize self
Specificity
Each adaptive response to foreign substances is different
- one lymphocyte can only recognize one antigen
Diversity
Body can recognize and respond to over a billion antigens
Memory
Recognition of antigens previously exposed to leads to stronger, faster response
Antibody (immunoglobulin) anatomy
- Y shaped protein
- 4 polypeptide chains, 2 heavy, 2 light
- chains are held together with disulfide bonds
- constant region: determines antibody class
- variable region: contains antigen binding site
- antigen binding site
Immunoglobulin G (Ig G)
- Monomer
- Most abundant in blood
- only ig that can pass through the placenta
Immunoglobulin A (Ig A)
- Dimer
- 2 Y units liked by 1 chain
- Secretory
- Found in body secretions (saliva, tears, mucous)
Ig M
- Pentamer
- 5 units linked by a J chain
- Potent agglutinater (cell clumping)
- Found in serum and B cell membrane
Ig E
- Monomer
- Involved in allergic reactions
- Releases histamine
- Found in serum and extracellular
Ig D
- Monomer
- Found on surface of B cells
- Not sure what it does
