Block C Lecture 1: Immune Anatomy Flashcards
Where does the naive precursor of a T cell undergo rearrangement of T-cell receptor genes?
In the bone marrow
(Lecture 1, Slide 4)
Where does the naive precursor of a T cell migrate to after the bone marrow?
The thymus
(Lecture 1, Slide 4)
Where does rearrangement of T-cell receptor genes occur?
The thymus
(Lecture 1, Slide 4)
Why are T-cell receptor genes rearranged?
To produce a unique TCR
(Lecture 1, Slide 4)
What does the unique TCR recognize?
A unique antigen in the MHC context
(Lecture 1, Slide 4)
What type of cell presents immature T cells with MHC in the thymus?
An Antigen-Presenting Cell (APC), such as a Dendritic Cell (DC)
(Lecture 1, Slide 4)
What happens to T cells that interact moderately with MHC in the thymus?
They are positively selected, receiving signals for survival
(Lecture 1, Slide 4)
What happens to T-cells that recognise MHC too strongly in the thymus?
They receive signals for apoptosis, and they are negatively selected
(Lecture 1, Slide 4)
Where do T cells migrate after their development in the thymus?
Into peripheral lymphoid organs
(Lecture 1, Slide 4)
How do T cells exit the thymus after their development?
Through lymphatics
(Lecture 1, Slide 5)
What is the direction of lymphatic drainage in the periphery?
Towards lymph nodes
(Lecture 1, Slide 5)
What 3 cell components make up lymph nodes?
T cells, B cells, and Antigen-Presenting Cells (APCs)
(Lecture 1, Slide 5)
What role do lymph nodes play in the immune system?
They act as headquarters that decide when and where immune responses need to occur
(Lecture 1, Slide 5)
Where are lymph nodes primarily centred?
Around the nose and mouth, lungs, and gut
(Lecture 1, Slide 5)
Why are lymph nodes centred around the nose, mouth lungs and gut?
Most infections are inhaled or swallowed, and these areas are common entry points for pathogens
(Lecture 1, Slide 5)
What are the various entry and exit points of lymph nodes?
Lymph nodes have various entry and exit points, with the main entry being through afferent lymphatic vessels
(Lecture 1, Slide 6)
What 2 things provide blood supply and serves as entry points for some lymphocytes in lymph nodes?
Arteries and veins
(Lecture 1, Slide 6)
What are the 2 points of entry for lymphocytes to enter lymph nodes?
Via High Endothelial Venules (HEVs) and afferent lymphatic vessels
(Lecture 1, Slide 6)
What do afferent lymphatic vessels allow?
Lymph inflow from the lymphatics
(Lecture 1, Slide 6)
What is lymph?
A clear-to-white fluid mainly containing white blood cells (lymphocytes)
(Lecture 1, Slide 6)
What are lymphatics?
Vessels, similar to blood vessels that transport lymph
(Lecture 1, Slide 6)
What 4 key areas are present in lymph nodes and what are their function?
Germinal center: Houses B cells
Paracortical area: Mostly contains T cells
Parafollicular area: Forms an interface where T and B cells communicate
Medullary cords: House antibody-producing plasma cells and macrophages
(Lecture 1, Slide 6)
Where does a dendritic cell circulate through the body?
Through blood and lymphatics
(Lecture 1, Slide 7)
How does a dendritic cell enter a lymph node and what does it bring with it?
Enters via afferent lymphatics, bringing the antigen to the lymph node
(Lecture 1, Slide 7)
Where does the interaction between B cells, T cells, and antigen-laden dendritic cells occur in the lymph node?
Follicular region
(Lecture 1, Slide 7)
What are the 2 types of cells dendritic cells can present to in the lymph node?
B cells and T cells
(Lecture 1,Slide 7)
What cells can B cells present to in the lymph node?
T cells
(Lecture 1, Slide 7)
How do B and T cells leave the lymph node after B cells and dendritic cells present antigens and where do they go?
They leave via efferent lymphatics to the rest of the body
(Lecture 1, Slide 7)
What are the two key areas in the spleen and what are their functions?
Red pulp, where RBCs are broken down/produced, and White pulp, containing the region where B, T, and Antigen-Presenting Cell (APC) interaction occurs
(Lecture 1, Slide 8)
What are Peyer’s Patches?
Organized surface structures in the gut
(Lecture 1, Slide 8)
How do dendritic cells in Peyer’s Patches sample antigens?
They can extend their pseudopods through and into the gut to sample antigens
(Lecture 1, Slide 8)
What is the role of M-cells in Peyer’s Patches?
M-cells are specialized Antigen-Presenting Cells (APCs) that can present antigens directly or indirectly (via dendritic cells) to T cells
(Lecture 1, Slide 8)
Where do cells that don’t recognise antigen leave the lymph nodes?
Via the cortical sinuses
(Lecture 1, Slide 9)
Where do lymphocytes respond to antigens?
In the peripheral lymphoid organs
(Lecture 1, Slide 10)
What must lymphocytes do after responding to antigens in the peripheral lymphoid organs?
Leave to reach the effector site
(Lecture 1, Slide 10)
How is the antigen recognised by a T cell?
When the antigen in presented by an MHC molecule
(Lecture 1, Slide 12)
What classes of MHC receptors do CD4+ (Helper) T cells and CD8+ (cytotoxic) T cells have?
CD4+ cells have MHC class II whereas CD8+ cells only have MHC class I
(Lecture 1, Slide 12)
What 2 paired protein chains does the T cell receptor (TCR) consist of?
α and ß (sometimes γ + δ)
(Lecture 1, Slide 12)
Do T cell receptors (TCRs) have a variable region?
Yes
(Lecture 1, Slide 12)
What domain is present near the tail of T cell receptors (TCRs)?
A transmembrane domain
(Lecture 1, Slide 12)
What is the cytoplasmic tail at the end of T cell receptors (TCRs) used for?
Interacting with signalling molecules
(Lecture 1, Slide 12)
What is the purpose of the T cell receptor (TCR)?
To recognise peptides presented by Major Histocompatibility Complex (MHC) molecules
(Lecture 1, Slide 13)
What tissues are immature dendritic cells present in?
All tissues (although sometimes with different names)
(Lecture 1, Slide 14)
What do dendritic cells do once they have taken up the antigen in the periphery?
They travel though the lymphatics to lymph nodes
(Lecture 1, Slide 14)
What do mature dendritic cells do after travelling to the lymph node after they have taken up the antigen?
They attempt to interact with T cells, and while most will not respond, some will and they will become activated upon being presented their specific antigen
(Lecture 1, Slide 14)
What do naïve T cells do?
They recirculate looking for phagocytes presenting their specific antigen
(Lecture 1, Slide 15)
How do T cells become activated after recognising their specific antigen on a phagocyte?
The T cell receptor (TCR) transmits a signal which activates the cell
(Lecture 1, Slide 15)
What is the first thing that happens after a T cell becomes activated after interacting with an APC?
The activated T cells start to proliferate
(Lecture 1, Slide 15)
Why do activated T cells temporarily lose the ability to leave the lymph node after proliferating?
To ensure the newly generated T cells are activated as well
(Lecture 1, Slide 16)
What enables activated T cells to regain the ability to leave the lymph node and return to the periphery to carry out their functions?
Differentiation into their effector functions
(Lecture 1, Slide 16)
What are 3 reasons the adaptive immune system is slower than the innate immune system?
As it requires cells to move, interact and produce cytokines in order to influence effector function, as the body must be able respond to threats anywhere
(Lecture 1, Slide 17)
What are the 4 phases, in order, of the timeline of the body’s response to an infection?
Establishment of infection
Inductive phase
Effector phase
Memory phase
(Lecture 1, Slide 18)
During what phase of the body’s reaction to an infection does the adaptive immune response start becoming activated?
The inductive phase, though it doesn’t become fully active until the effector phase
(Lecture 1, Slide 18)
What happens when the bodies response to infection reaches the inductive phase?
Damage-associated molecular pattern molecules (DAMPs) are produced and Pathogen-associated molecular pattern molecules (PAMPs) will further enhance response
(Lecture 1, Slide 18)
When does the body response to infection reach the effector phase?
Once activated T cells are brought back from the lymph and thus begin to clear the infection
(Lecture 1, Slide 18)
What activates the immune system?
Inflammatory inducers which indicate the presence of pathogens or tissue damage
(Lecture 1, Slide 19)
How is memory induced in the immune system?
Through the production and maintenance of memory T cells
(Lecture 1, Slide 19)
How long can memory T and B cells persist?
Years, decades, or can even be life-long
(Lecture 1, Slide 19)
