Overview of the Adaptive Immune System

Question 1

What are the 2 main ways that adaptive immune system is different to innate

Answer 1

• specificity
• memory (aka anamnestic response)

Question 2

Does the innate or the adpative immune system recognise PAMPs?

Answer 2

Both

Question 3

What is meant by the danger hypothesis?

Answer 3

This is one way that we think the adaptive immune system spots pathogens

• T cells will recognise PAMPs but they also need co-stimulation by CD28 to tell us that the pathogen is causing damage!
• presence of pathogens is associated with tissue damage/DAMPs

Question 4

How does the adaptive immune system differentiate between a v harmful organism and a non harmful one?

Answer 4

• This is by the danger hypothesis
• So saying that a T cell needs to recognise the PAMPs BUT ALSO needs co stimulation by activation of CD28 (or recognition of DAMPS) to activate them as these are signs of tissue damage
• in later lectures they talk about how when a dendritic cell is bound to TCR, the T cell also needs other signals from the d cell including signals from PRRs from the detection of PAMPs

Question 5

Name 4 ways that the adaptive immune system recognises pathogens

Answer 5

• By recognising generic recognisible features (e.g. PAMPs)
• By recognising that there is damage associated with the presence of a pathoge
• By recognising previously encountered ‘bad guys’
• By recognising self vs non-self material

Question 6

In the context of adaptive immunity, what is meant by effectors?

Answer 6

Question 7

What infection causes the below MRI scan (white on the left is water and white on the right is inflammation)?

Answer 7

Toxiplasmosis

Question 8

Give 3 examples of ways that we can lose B cell counts

Answer 8

• Congenital agammaglobulinaemia
• Common Variable Immunodeficiency (CVID)
• Novel biologics - Rituximab

Question 9

Give 3 examples of how we can lose T cell count

Answer 9

• Severe Combined Immunodeficiency (SCID)
• DiGeorge syndrome - thyme failure
• Aquired - HIV/ Chemotherapy/ Novel biologics

Question 10

Do NK cells have memory?

Answer 10

Generally no, but there is a subset called NK memory that does

Question 11

Out of all the WBCs and some extra factors - split them into innate vs adaptive (remember that it is more complicated than this)

Answer 11

Question 12

What is meant by ‘bridging cells’?

Answer 12

The cells in between innate and adaptive

Question 13

Name some bridging cells

Answer 13

• Memory NK Cells
• iNKT cells
• V𝛿2⁺ γ𝛿 T cells
• MAIT

Question 14

What is a MAIT cell (what does it stand for)?

Answer 14

Mucosal associated invariant T cell

Question 15

Explain why a MAIT cell is not in the adaptive system?

Answer 15

• It is like an alphabeta T cell (adaptive) as it has memory and clonal proliferation
• BUT it is pre-programmed as there are some targets that are so common that the body pre-programs some cells - MAIT cells

Question 16

CD20-positive cells are also known as what?

Answer 16

B lymphocytes

Question 17

What is meant by a naive cell?

Answer 17

• Before a cell becomes a memory cell it is a naive cell
• A naïve T cell is a T cell that has matured and been released by the thymus but has not yet encountered its corresponding antigen

Question 18

What is meant by lymohocyte multidimensionality?

Answer 18

Each lymphocyte type can be described in multiple ways – so e.g. by functionality, shape, lineage, location etc.

Question 19

What 2 terms can we use to define a lymphocyte based on location?

Answer 19

• Tissue resident memory cells (TRM)
• Marginal zone B cells

Question 20

Describe clonal selection

Answer 20

• Happens in B cells and T cells
• One clone is expanded (proliferates) and each clone is specific to 1 antigen

Question 21

In clonal selection of B cells, one B cell has one specific what?

Answer 21

Immunoglobulin

Question 22

In clonal selection of T cells, one T cell has one specific what?

Answer 22

T cell receptor (TCR)

Question 23

Do B cells have a B cell receptor like T cells?

Answer 23

Yes but they seecrete it - this is what antibodies are
- T cells do NOT secrete it

Question 24

B cells mature in the {?}, but T cells mature in the {?}

Answer 24

• B cells mature in the bone marrow
• but T cells mature in the thymus

Question 25

What does MHC class 1 present to?

Answer 25

CD8+

Question 26

What does MHC class 2 present to?

Answer 26

CD4+

Question 27

Specialised antigen-presenting cells process and present peptides on MHC class {?}.

Answer 27

Specialised antigen-presenting cells process and present peptides on MHC class 2

Question 28

All cells process their intracellular contents and present antigens on MHC class {?}

Answer 28

All cells process their intracellular contents and present antigens on MHC class 1

Question 29

Which MHC is responsible for the main protection against viruses?

Answer 29

MHC 1

Question 30

Explain what thymic selection is and how it works

Answer 30

In the Thymus (which dies after puberty) T cells have to bind to MHC1 enough with their TCR otherwise it dies (death by negelect)

And if it binds self proteins then it also dies

• now have a population of highly specifc Naiive T cells

Question 31

Outline T cell differentiation/maturation pathway (terminal and start cells)

Answer 31

Once the T cell binds its specfic antigen - it differentiates

Question 32

What are T effector memory cells?

Answer 32

TEM: Effector Memory Cells

• Short-lived population
• Continually replenished
• Double time about 15 days

Question 33

What are TCM?

Answer 33

TCM: Central Memory Cells

• Turnover at a significant rate
• Double time about 48 days

Question 34

What is the function of T regulatory cells?

Answer 34

Regulates/inhibits the immune system

Question 35

What is meant by positive and negative selection?

Answer 35

B and T cells undergo positive selection to make sure that they are recognising an antigen/MHC and then negative selection to make sure they are not recognising self antigens

Question 36

What molecule do tissue resident T cells have on the surface specifically?

Answer 36

CD69