When would immunosuppression be utilitised?
Patients may be artificially immunosuppressed in the event of an autoimmune disease
Describe the properties of the skin as a physical barrier to infection
It is constantly renewed
It has a low pH
It has low oxygen tension
Sebaceous glands secrete hydrophobic oild whick make it hard for pathogens to bind
Mucous line all _____ ________ that come into contact with the ___________
Mucous contains many constitutes which can fight potential pathogens, what are these?
- Secretory IgA
- Antimicrobial peptides
- Lactoferrin - starve invading bacteria of iron
What are commensal bacteria?
Bacteria that reside in the body and on epithelial surfaces naturally.
They have a symbiotic relationship with the body and can eradicate most normally infections
They ensure there is no undefended ecological niche
The components of the immune system can be split into which two categories?
- Humoral immunity (soluble factors)
Which 3 main groups of cells are involved in the immune system?
When a cell is infected with a virus what will it secrete?
Interferons (alpha and beta)
The antiviral state inititiated by interferons achieves what?
It down regulates protein synthesis which slows virus production
What is an antigen?
An substance able to stimulate an adaptive immune response - it can be protein, carbohydrate, nucleic acid, lipid, metal etc
Where are T and B cells formed?
Where do B cells mature?
Where do T cells mature?
In response to an infection B cells will produce what?
Antibodies and memory cells
What are the two types of T cell?
Helper T cell (CD4+)
Cytotoxic T cell (CD8+)
How does a virus evade the immune system?
It will usually hide within body cells
How can cytotoxic T cells discover viruses hiding in body cells?
The host cell constantly samples its cytoplasm and displays proteins on its surface - this is mediated by MHC class 1 proteins
These displayed proteins can "show" cytotoxic T cells which cells are infected
How do viruses evade the process of cytoplasm sampling mediated by MHC class I proteins?
They downregulate the production of MHC class I proteins
This reduced cytoplasm sampling
How do natural killer (NK) cells retaliate to viruses that downregulate MHC class I production?
NK cells can detect a lack of MHC class I proteins on a cell surface
They can then attack and destroy such cells
How are parastitic works (helminths) attacked by the immune system?
Antibodies and mast cells
What is the complement system and where is it produced?
Family of around 30 different proteins produced in the liver
How does the complement system function?
When activated, the proteins activate eachother in a cascade fashion
This involves great amplification and playes a role in inflammation
When do monocytes differentitate into macrophages?
When they exit the blood and migrate to peripheral tissues
What are Kupffer cells?
Macrophages of the liver
What are mesangial cells?
Macrophages of the kidney
What are macrophages of the nervous sytem called?
How can neutrophils be differentiated from macrophages?
Their multi-lobed nucleus
What is the role of dendritic cells?
They engulf pathogens, phagoytose and then present antigens on their surface to T cells
What are the main functions of neutrophils?
Killing and degredation
What are the main functions of macrophages?
Killing, degregation, wound healing, anti-inflammatory and antigen presentation