Pathogens
Viruses
- Not alive
- Can be transferred from animal to humans
- DNA viruses / RNA viruses - Rabies (hondsdolheid): 100% death rate
Bacteria Fungi, Protozoa, Worms
- Prokaryotic - Eukaryotic
- Gram + / Gram - - More difficult to attack, because they share a
- Cocci/Bacilli lot of structures with humans
Principles of innate immunity
Anatomic and chemical barriers
- Avoidance mechanisms prevent exposure to microbes
- Reducing or eliminating pathogens
Activation immune system
- Inflammatory inducers -> indicate the presence of pathogens or tissue
damage
- Detected by sensor cells by expressing various innate recognition
receptors -> produce a variety of mediators -> act on target tissues
Immunological Biotechnology 2
,Chapter 1 Laura van den End
Cells of innate immunity
Short lived, produced during immune response, leave blood,
migrate to place of infection or inflammation
In many tissues;
phagocytic
Uptake of Ag: Release of substances that affect vascular
- Phagocytosis permeability (allergic responses, protection of
- Macropinocytosis mucosal surfaces)
Take up a variety of micro-organisms,
Help induce inflammation
Activate complement system
Sensor cells that mainly activate other immune cells
Deficiency in neutrophils: leads to massive bacterial infection
Fatal if untreated
- Sensor cells express Pattern
Recognition Receptors (PRRs) ->
Defense against parasites self vs non-self
- Transmembrane: TLR ->
recognize patterns ->
proteins are being produced
to kill the intruder
- Cytoplamic: NLR -> sense
intracellular bacterial
invasion
Inflammatory mediators - LPS is typical for bacteria
Immunological Biotechnology 3
, Chapter 1 Laura van den End
Infection triggers inflammatory response
- Macrophages encountering bacteria -> triggered to release cytokines (left panel) -> increase
permeability of blood vessels -> allowing fluid and proteins to pass into the tissues (center panel).
- Macrophages also produce chemokines -> direct the migration of neutrophils to the site of infection.
- The stickiness of the endothelial cells of the blood vessel wall is also changed, -> circulating cells of the
immune system adhere to the wall -> crawl through it;
- First neutrophils and then monocytes are entering the tissue from a blood vessel (right panel).
- Accumulation of fluid and cells at the site of infection -> redness, swelling, heat, and pain.
- Neutrophils and macrophages are the principal inflammatory cells.
- Later in an immune response, activated lymphocytes can also contribute to inflammation.
Natural killer cells
- Effector cells that share similarities with lymphoid lineages of the
adaptive immune system
- Third lineage of lymphoid cell
- No Ag specific receptors
- Large, circulate in blood
- Recognize and kill abnormal cells (tumor cells, virus-infected cells)
- Large, granular, lymphoid-like cells with important functions in innate
immunity, especially against intracellular infections
Immunological Biotechnology 4
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