REVISION Flashcards
What is the first line of defence against pathogens?
Outer barriers e.g. Epithelial Layer (skin)
Where do secondary lymphoid tissues reside?
lining the mucosa and throughout the body
Through what do immune cells migrate?
Lymphatic system
What is the mucosa known as in infection?
Primary site of infection
Function of the outer mucosal layer?
Trap microbes - slow things down
How does the inner mucosal layer function?
It is full of AMPS which bind any microbes that enter through the mucosal layer
Where do AMPS reside?
Inner mucosal layer
What is the epithelial function of mucins?
Protect epithelial cells from stress induced damage
Bacterial function of mucins?
Prevent biofilm formation
MUC2 - where? membrane bound or secreted gel forming?
Intestine - Secreted gel forming
MUC3 - membrane bound or secreted gel forming?
Membrane bound - forms the glycocalyx
MUC6 - where? why?
Colon - there is a higher microbial load here so mucus is thicker
Where are AMPS derived from
Epithelial
Function of defensins?
Kill bacteria or inhibit growth
Where are ALPHA defensins found?
Neutrophils, macrophages and Paneth cells of intestine
Where are beta defensins expressed?
On epithelial surfaces
Role of complement 3?
Amplification and opsonization - C3A recruits immune cells by inflammation and C3B cells attack to the microbe (opsonisation)
What is the membrane attack complex?
a combination of proteins formed on the surface of pathogen cell membranes as a result of the activation of the complement system
c5 function?
Forms the MAC
Function of MAC?
Forms a pore on the cell membrane which causes calcium ion influx and ultimately cell death
What initiates the classical complement pathway?
An antibody bound microbe
What initiates the alternative complement pathway?
A free microbe
What initiates the lectin pathway?
Binding of PAMPS onto PRR
List the 3 types of PRRs
TLR, RLR, CDS
TLR2 - positive or negative?
a membrane bound TLR that responds to gram positive bacterial cell wall components e.g. PEPTIDOGLYCAN and LIPOPEPTIDES- to provoke an immune response
TLR 4 - positive or negative?
a central role in the control of bacterial infections through the recognition of LPS molecules from GRAM-NEGATIVE
Function of the Peyers Patch?
Samples everything in the mucosa - same function as the tonsils - bacteria and viruses may replicate in either organ causing inflammation
What happens in the germinal centre of the lymph nodes?
Macrophages and dendritic cells migrate here and there is already lots of B and T cells that will mature here - develop into long life immunity
What transports immune cells?
Lymphatic vessels
What response is seen as an anti-allergy response?
TH2 - the induce an inflammatory response and recruit eosinophils to the site
What cells do eosinophils activate?
Mast cells and basophils
Where are T cells educated?
Thymus
Do natural killer cells require education?
No
What is a NKT mechanism of action?
Release of perforin and granzyme onto target cell causing cell death
What is the difference between M1 and M2 macrophages?
M1 macrophages are mainly involved in pro-inflammatory responses and M2 macrophages are mainly involved in anti-inflammatory responses
What cell types are APCs?
Macrophages, dendritic cells, and B cells
What is a dendritic cells main function?
The activation of T cells to produce specific antibodies
What differentiates Natural Killer cells from Cytotoxic CD8 cells?
CD8 cells require education and activation
What does T cell education mean?
All self antigens are presented in the thymus which means T cells can differentiate self from foreign microbes
What stage of life displays the highest level of T cell education?
Puberty
