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Flashcards in Immunology 7 Deck (23)
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1
Q

What is the main subset of APC

A

Dendritic cells

2
Q

|”What do dendritic cells do?

A

Exist in tissues where they do surveillance. They acquire antigen and then move to lymph nodes where they mature and present the antigen on MHC. This is detected by T cells and then stimulated to proliferate into effector cells and migrates to source of infection.

3
Q

Both T cells and Dendritic cells are circulating

A

T

4
Q

What is the 3 signal model that licenses a response?

A
  1. Antigen recognition
  2. Costimulation
  3. Cytokine release

IF NOT ALL 3, T cell WONT BE ACTIVATED

5
Q

What do CD8 cells (CTL) do?

A

Destroy target cells (e.g. viral infected cells/tumours)

6
Q

ALL CELLS PRESENT SELF ANTIGEN ON MHC 1. But then how are viral antigens recognised by cd8?

A

As well as displaying self antigen, some viral antigen is also displayed. CD8 recognises this and destroys the cell.

7
Q

What happens when cytotoxic effectors recognise their target cell?

A
  1. Polarisation of cell containing cytoxic vesicles
  2. Granule release by cytotoxic t cells
  3. Inducing apoptosis
8
Q

Explain how perforin and granzyme works

A
  1. CD8+ injects perforin into target cell membrane
  2. Creates pore in membrane and allows granzyme to work.
  3. Granzyme binds to Caspase enzyme - triggers cascade which induces apoptosis.
9
Q

Explain the fas pathway of apoptosis.

A
  1. CD8 cell has fas ligand (fasL)
  2. Target cell has fas receptor
  3. Once fas has bound, it releases caspases - triggers apoptosis.
10
Q

What does CD8 drive?

A

Viral evolution

11
Q

What are the effector functions of CD4 cells?

A
  1. Macrophage activation
  2. Delayed type hypersensitivity response
  3. B cell activation
  4. Regulation

MAJOR ROLE IS TO PRODUCE CYTOKINES FOR DOWNSTREAM RESPONSES

12
Q

What are the 5 subsets of T helper cells.

A
  1. Th1 - pro-inflammatory (boosts cellular response by activating gamma IF and macrophages)
  2. Th2 - boosts anti-multicellular organism response
    - produce IL 4 / IL 5 / IL 13
  3. Follicular T helper cells
    - essential for antibody production
    - produce IL 21, reside in B cell follicles
  4. Th17 cells - drive antibacterial response
  5. T regulatory (Treg) -
13
Q

DENDRITIC CELLS PRODUCE CYTOKINES WHICH TELL THE CD4 CELL WHAT TYPE OF HELPER CELL IT WILL BE

A

T

14
Q

What defines a T helper cell?

A

The cytokines they produce and the TFs they use

15
Q

What is Delayed Type Hypersensitivity?

A

Reaction to an antigen.

Mainly defence against intracellular pathogens by eradicating them.

However, if antigen not eradicated, chronic stimulation can occur (or granuloma formation)

If the antigen is not a microbe, DTH can cause tissue injury without protection

16
Q

What do activated macrophages express?

A

Increased levels of CD40 and TNF- a receptors.

They secrete more TNF - a.

T cells and macrophages cross talk via cytokines

17
Q

Allergy is driven by?

A

CD4 th2 cells - eosinophil activation

18
Q

What are the 2 phases of a DTH reaction?

A
  1. Sensitisation

2. Effector

19
Q

What are differences between T cell memory and B cell memory?

A
  1. T cells do not undergo isotope switching or affinity maturation unlike B cells (which allows B cell responses to improve over time)
20
Q

Differences between naive T cell and memory T cell?

A

Memory T cell has different cytokine receptor

Memory T cells proliferate faster

21
Q

What are the different subsets of memory T cells?

A

Effector memory - local to site of infection

Central memory - go back to spleen/lymph nodes

22
Q

What is T cell exhaustion?

A

Over time, especially in chronic infections, the CD8 pool contracts.

CD8 Cells start to exhibit PD1 on their cell which makes them harder to activate.

23
Q

What are the good and bad things T cells have?

A

+ pathogen cleared

  • autoimmunity
  • rejection