What does the upper GI tract consist of?
What does the lower GI tract consist of?
In basic terms, what are the 2 kinds of bacteria found in the GI tract?
What are some examples of challenges of antigen processing in the GI tract?
Develop exogenous tolerance
Develop an effective immune response
What is self-tolerance?
Non-responsiveness of the immune system to self-antigens
What is exogenous tolerance?
Non-responsiveness of the immune systemto newly encountered environmental antigens that are harmless
What are examples of different facets to normal antigen processing in the GI tract?
Innate immune response
Antigen presenting cells
Tolerance versus activated of adaptive immune response (T cell)
Soluble mediators of immunity
How does the epithelial layer provide protection?
Specialised tight junctions that regulate permeability
How does the mucus layer provide protection?
Physical barrier keeping microbes from host cells
What are examples of antigen presenting cels?
What are examples of soluble mediators of immunity?
Chemokines and cytokines
What are the 2 different parts of the immune system?
Innate immune system
Adaptive immune system
What kind of immune cells are innate?
Granulocyte (neutrophil, eosinophil, basophil)
Natural killer cell
What kind of immune cells are adaptive?
CD4+ T cell (memory)
CD8+ T cell (memory)
B cell (memory), which become plasma cells that produce antibodies
Where do all cells of the immune system originate from?
Haematopoitic stem cell which comes from bone marrow
What are the 2 things that a haematopoietic stem cell can differentiate into?
Myeloid progenitor cell
Lymphoid progenitor cell
What does myeloid progenitor cell differentiate into?
All cells of innate immune system (except natural killer cells)
What do lymphoid progenitor cells differentiate into?
All adaptive immune system cells
Natural killer cells
Which immune system causes inflammation?
Innate immune system
What is a key determinant of T cell differentiation?
The cytokine milieu
How do cytokines vary in terms of inflammation?
Some are pro-inflammatory and some are anti-inflammatory
What is a T cell called before it has differentiated into its subtype?
Naive T cell
What are peyer's patches?
Small masses of lymphatic tissue found throughout the ileum region of the small intestine
What do peyer's patches allow?
Sufficient sampling of particulate antigens and delivery to antigen presenting cells
What is a macrophage?
Type of phagocyte which is responsible for detecting, engulfing and destroying pathogens and apoptotic cells
What is the first line of defence system in the gut?
What are functions of macrophages?
Sampling of particulate antigens
Phagocytic (ingests harmful pathogens or dying/dead cells)
Secrete cytokines (such as IL-10 required for the survival of FoxP3 and Treg cells)
Antigen presenting cells to modulate adaptive immune response
Where are dendritic cells found in the GI tract?
Lamina propria and peyer's patches
Why are dendritic cells important for mucosal immune responses?
Efficient sampling of antigen
Different dendritic cell subsets give rise to distinct T cell responses (such as tolerance vs immunity)
Different subsets distinguished by cell markers)
Present antigen to naive T cell
What to dendritic cells do after they have sampled gut bacteria and gut antigens?
Migrate to major lymph nodes