Lecture 12 week 7

Question 1

Where are MHC markers expressed?

Answer 1

Expressed on the surface of a cell

Question 2

What are MHC markers

Answer 2

Proteins expressed on surface of a cell

Question 3

What do MHC markers do?

Answer 3

Used primarily in recognition of pathogens in immune system

Also in self recognition

Question 4

What are antigens?

Answer 4

On the surface of pathogens that immune system recognizes as specific threat

Question 5

MHC displays both ________

Answer 5

Self and non self antigens

Question 6

What does step 1 include? (adaptive immune system)

Answer 6

Invader enters body

Question 7

What does step 2 include (adaptive immune system)

Answer 7

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

Question 8

What does step 3 include (adaptive immune system)

Answer 8

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

Question 9

What does step 4 include (adaptive immune system)

Answer 9

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

Question 10

What is activated when cell mediated (T cell) response?

Answer 10

• Naïve cytotoxic T cell activated

Question 11

What is activated when antibody mediated (B cell) response?

Answer 11

• Naïve B cell activated`

Question 12

What does step 5 include (adaptive immune system)

Answer 12

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)

Question 13

What does step 6 include? (adaptive immune system)

Answer 13

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)

Question 14

What does step 7 include? (adaptive immune system)

Answer 14

Memory T cells stored for continued surveillance

Question 15

How is the encounter remembered?

Answer 15

In the form of memory cells

Question 16

Where are memory cells stored?

Answer 16

In bone marrow and thymus

Question 17

How does negative feedback work?

Answer 17

T suppressor (regulatory, Foxp3+) cells
* Suppress activation of the immune system, particularly production of T
helper cells
* Important in allowing tolerance to self antigens

Question 18

What does too little T supressor response lead to ?

Answer 18

association with autoimmune disease,
allergies, graft rejection, inflammatory bowel disease

Question 19

What does too much T suppressor response lead to?

Answer 19

possible connection to cancer &
increased incidence of infectious diseases

Question 20

What are autoimmune disorders?

Answer 20

• Occur when the body’s immune system attacks & destroys healthy
  body tissue by mistake
• There are 80+ types

Question 21

What is an example of an autoimmune disorder

Answer 21

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