The Immune System: Immunization and Human Disease Flashcards
What is the first main, important characteristic of the adaptive immune system?
IMMENSE DIVERSITY of receptors of B and T lymphocytes
- Variability in the shapes of the proteins, different combinations/sequence variations in the VARIABLE REGIONS => Determines which shape epitope corresponds.
- We have 1M different B cell receptors, 10M T cell receptors
What is the second main, important characteristic of the adaptive immune system?
SELF-TOLERANCE: Lack of reactivity against one’s own molecules.
Ability to recognize our own host cells apart from the pathogens.
In a healthy immune system, SELF-REACTIVE combinations are identified and rapidly DESTROYED, RENDERED NONFUNCTIONAL
What is the third main, important characteristic of the adaptive immune system?
PROLIFERATION (duplication): Once activated, a B or T cell undergoes multiple cell divisions to produce a clone of identical, appropriate cells
The one that gets woken up by binding to an antigen that binds to its receptor –> the cells proliferate.
Many different versions of the defender, whichever one gets woken up clones themselves.
What is the fourth main, important characteristic of the adaptive immune system?
IMMUNOLOGICAL MEMORY: Post-proliferation, there are two different cells that are generated from the process…
(a) Short-lived activated EFFECTOR (plasma) CELLS, that act immediately against the antigen = Active duty!
* *Die upon being used
(b) Long-lived MEMORY CELLS that can give rise to effector cells if the same antigen is encountered again = Inactive
* *Put into storage, in case the proliferation process is needed
Why is immunological memory so important?
It is key to long-term protection against diseases. It is generated by a PRIOR INFECTION or VACCINATION.
-Prior exposure to antigen A results in STRONGER secondary responses
- Exposure to Antigen A
After exposure, the production of antibodies to A ramps up and fights off the infection.
Eventually, the plasma cells meet the natural end of their lives.
2. Exposure to Antigens A and B The response (concentration of antibodies) is much higher in responding to antigen A than to antigen B = Ability to mobilize the antibodies A really quickly and massively.
NOTE: This is antigen-specific!
The response to Antigen B almost looks like the initial exposure response to antigen A.
What is active immunity?
Develops naturally when a pathogen invades the body and elicits a primary or secondary immune response.
Example: Natural infection; Immunization
What is passive immunity?
Provides immediate, short-term protection.
Example: Antibodies transferred from mama bear’s breast milk to baby’s bloodstream
**Not built-in/learned, came from someone else.
How are vaccines made?
Conventional vaccines: Introduce the host defense system to a small piece of the protein coat (antigen) of DESTROYED/DE-ACTIVATED VIRUSES = Dead viruses
RNA vaccines: DON’T inject the antigen, just the instructions for host cells to build the antigens themselves = Messenger RNA; we generate the correct epitope ourselves!
How can infection rates be so low?
VACCINATION!
What is an antigenic variation?
The human influenza virus mutates rapidly, meaning new flu vaccines must be made each year.
Some viruses have warped versions of epitopes, unrecognizable to the existing vaccine.
What is immune rejection?
Cells transferred from one person to another can be attacked by immune defenses.
This complicates blood transfusions, transplants of tissues/organs.
= Need to find a ‘match’!
Blood types are related to…
Antigens!
The antigens on red blood cells determine whether a person has blood type A (A antigen), B (B antigen), AB (both A and B antigens), or O (neither antigen).
Antibodies to non-self blood types can exist in the body!
How do allergies work?
Allergies are exaggerated (hypersensitive) responses to antigens called ALLERGENS.
Mast cells release histamine and other mediators, causing vascular changes –> Typical allergy symptoms
What is anaphylactic shock?
An extreme allergic response which can be life-threatening
___________ reactions tend to be worst than ____________ reactions.
Secondary; initial
