Innate Immunity Flashcards
Define innate immunity
Non-specific responses that occur with the presence of a pathogen in the body
What are the first lines of defence?
Behavioural, societal, cultural
First lines of individual defence
Physical membrane e.g. skin and membranes
What kind of defences does the body have?
Epithelia, chemical defences and defensins
How is epithelia a good barrier?
- Hair on skin forms barrier
- Tight junctions; secrete mucous
Examples of chemical defences
Sweat, sebum, lactic acid, lysosomes, stomach pH
What are defensins?
They are a broad spectrum of positive peptides that defend the host. Target membrane
How can epithelia be risky?
Some epithelia need to be kept moist e.g. eye, respiratory system –> conjunctivitis or syphilis etc.
When passive barriers fail, what are the “key players in immunity”?
- lymphatic system
- cardiovascular system
- effector and signalling molecules
- lymphoid cells - T cells in thymus, B cells in marrow
Innate systems
- barriers
- phagocytes
- natural killer cells
- interferons
- complement
- inflammation
Which defences require no pathogen recognition?
Stomach acid and defensins
Pathogen recognition: general recognition
F-met prokaryote proteins
Lipopolysaccharides for gram negative bacteria
Foreign nucleic acids
Are pattern recognition receptors soluble?
Some are soluble, some are membrane-bound
What are collectins?
Soluble pattern recognition receptors
bind to specific carbohydrates, bind to phagocytes, some interact with complement
Example of soluble pattern recognition receptors
Collectins
Example of membrane-bound pattern recognition receptors
Toll-like receptors
What are Toll-like receptors?
Membrane-bound pattern recognition receptors
found on epithelia of macrophages, bind to pathogen proteins, promote inflammation
What is the complement system?
20+ soluble proteins that evoke lysis, phagocytosis and inflammation
What is c3b?
Part of the complement that triggers membrane attack complex formation –> causes cell to blast by taking in water
What are interferons secreted by?
Lymphocytes, macrophages, virus-infected cells etc.
secretion evoked by dsRNA
What are natural killer cells?
Cells that destroy bacteria, virus-infected cells and tumour cells
