Lecture 12 week 7 Flashcards
Where are MHC markers expressed?
Expressed on the surface of a cell
What are MHC markers
Proteins expressed on surface of a cell
What do MHC markers do?
Used primarily in recognition of pathogens in immune system
Also in self recognition
What are antigens?
On the surface of pathogens that immune system recognizes as specific threat
MHC displays both ________
Self and non self antigens
What does step 1 include? (adaptive immune system)
Invader enters body
What does step 2 include (adaptive immune system)
Detetction:
A macrophage encounters, engulfs, & digests the invader (antigen e.g. a bacterium)
* The macrophage places a piece of the invader (antigen) on its surface with the self (MHC) marker
What does step 3 include (adaptive immune system)
Alert:
* The macrophage presents the antigen to a helper T cell & secretes a chemical that activates the helper T cell
* Complex set of signals to activate helper T cell (recognition + verification to ensure it’s responding to non-self)
-During Step 3, helper T cell divides & transforms into effector helper T cell
What does step 4 include (adaptive immune system)
Alarm:
Effector helper T cell activates:
A. Cell-mediated (T cell) response
* Naïve cytotoxic T cell activated
B. Antibody-mediated (B cell) response
* Naïve B cell activated
What is activated when cell mediated (T cell) response?
- Naïve cytotoxic T cell activated
What is activated when antibody mediated (B cell) response?
- Naïve B cell activated`
What does step 5 include (adaptive immune system)
Building specific defenses:
* Naïve cytotoxic T cell divides (amplification) into effector cytotoxic T cell (Step 6: Defense), & memory cytotoxic T cell (Step 7: Continued surveillance)
What does step 6 include? (adaptive immune system)
Defense
* Effector cytotoxic T cells targets cells displaying foreign antigen (cells infected with intracellular pathogen, cancer cells, cells of organ transplants, etc.), & kills them by chemical means e.g. perforins (punch holes in the target cell
membrane)
What does step 7 include? (adaptive immune system)
Memory T cells stored for continued surveillance
How is the encounter remembered?
In the form of memory cells
Where are memory cells stored?
In bone marrow and thymus
How does negative feedback work?
T suppressor (regulatory, Foxp3+) cells
* Suppress activation of the immune system, particularly production of T
helper cells
* Important in allowing tolerance to self antigens
What does too little T supressor response lead to ?
association with autoimmune disease,
allergies, graft rejection, inflammatory bowel disease
What does too much T suppressor response lead to?
possible connection to cancer &
increased incidence of infectious diseases
What are autoimmune disorders?
- Occur when the body’s immune system attacks & destroys healthy
body tissue by mistake - There are 80+ types
What is an example of an autoimmune disorder
E.g. Celiac Disease causes digestive issues upon consuming gluten
(found in wheat & other grains)
* Gluten describes the protein fraction of wheat, barley, & rye which have high
concentrations of glutamine & proline (cannot be completely digested by
humans)
* Partially-digested peptides initiate innate & adaptive immune response in
those with Celiac Disease
* Immune system attacks peptides in small intestine, damaging it & hindering
its function
* Non-celiac gluten sensitivity – pathophysiology not yet understood
