Overview of the Adaptive Immune System Flashcards
What are the 2 main ways that adaptive immune system is different to innate
- specificity
- memory (aka anamnestic response)
Does the innate or the adpative immune system recognise PAMPs?
Both
What is meant by the danger hypothesis?
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
How does the adaptive immune system differentiate between a v harmful organism and a non harmful one?
- 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
Name 4 ways that the adaptive immune system recognises pathogens
- 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
In the context of adaptive immunity, what is meant by effectors?
What infection causes the below MRI scan (white on the left is water and white on the right is inflammation)?
Toxiplasmosis
Give 3 examples of ways that we can lose B cell counts
- Congenital agammaglobulinaemia
- Common Variable Immunodeficiency (CVID)
- Novel biologics - Rituximab
Give 3 examples of how we can lose T cell count
- Severe Combined Immunodeficiency (SCID)
- DiGeorge syndrome - thyme failure
- Aquired - HIV/ Chemotherapy/ Novel biologics
Do NK cells have memory?
Generally no, but there is a subset called NK memory that does
Out of all the WBCs and some extra factors - split them into innate vs adaptive (remember that it is more complicated than this)
What is meant by ‘bridging cells’?
The cells in between innate and adaptive
Name some bridging cells
- Memory NK Cells
- iNKT cells
- V𝛿2+ γ𝛿 T cells
- MAIT
What is a MAIT cell (what does it stand for)?
Mucosal associated invariant T cell
Explain why a MAIT cell is not in the adaptive system?
- 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
CD20-positive cells are also known as what?
B lymphocytes
What is meant by a naive cell?
- 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
What is meant by lymohocyte multidimensionality?
Each lymphocyte type can be described in multiple ways – so e.g. by functionality, shape, lineage, location etc.
What 2 terms can we use to define a lymphocyte based on location?
- Tissue resident memory cells (TRM)
- Marginal zone B cells
Describe clonal selection
- Happens in B cells and T cells
- One clone is expanded (proliferates) and each clone is specific to 1 antigen
In clonal selection of B cells, one B cell has one specific what?
Immunoglobulin
In clonal selection of T cells, one T cell has one specific what?
T cell receptor (TCR)
Do B cells have a B cell receptor like T cells?
Yes but they seecrete it - this is what antibodies are
- T cells do NOT secrete it
B cells mature in the {?}, but T cells mature in the {?}
- B cells mature in the bone marrow
- but T cells mature in the thymus
What does MHC class 1 present to?
CD8+
What does MHC class 2 present to?
CD4+
Specialised antigen-presenting cells process and present peptides on MHC class {?}.
Specialised antigen-presenting cells process and present peptides on MHC class 2
All cells process their intracellular contents and present antigens on MHC class {?}
All cells process their intracellular contents and present antigens on MHC class 1
Which MHC is responsible for the main protection against viruses?
MHC 1
Explain what thymic selection is and how it works
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
Outline T cell differentiation/maturation pathway (terminal and start cells)
Once the T cell binds its specfic antigen - it differentiates
What are T effector memory cells?
TEM: Effector Memory Cells
- Short-lived population
- Continually replenished
- Double time about 15 days
What are TCM?
TCM: Central Memory Cells
- Turnover at a significant rate
- Double time about 48 days
What is the function of T regulatory cells?
Regulates/inhibits the immune system
What is meant by positive and negative selection?
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
What molecule do tissue resident T cells have on the surface specifically?
CD69
