Changes

[[Image:PRRs.jpg|thumb|right|150px|Pattern Recognition Receptors - B. Catchpole, RVC 2008]]

[[Image:PRRs.jpg|thumb|right|150px|Pattern Recognition Receptors - B. Catchpole, RVC 2008]]

The innate immune system recognises components of pathogens which are intrinsically foreign (i.e. not present on normal mammalian cells), such as:

The innate immune system recognises components of pathogens which are intrinsically foreign (i.e. not present on normal mammalian cells), such as:

**Lipopolysaccharides of gram-negative bacteria

*Lipopolysaccharides of gram-negative bacteria

**Peptidoglycans of gram-positive bacteria

*Peptidoglycans of gram-positive bacteria

**Mannose sugars

*Mannose sugars

**D-isoform amino acids

*D-isoform amino acids

These are known to the body as foreign as they are expressed as '''pathogen-associated molecular patterns''' (PAMPs)

* PAMPs are recognised by '''pattern recognition receptors''' (PRRs) expressed on mammalian cells

** Pattern recognition receptors are expressed on many different cell types, not just on phagocytes

These are known to the body as foreign as they are expressed as '''pathogen-associated molecular patterns''' (PAMPs) which are recognised by '''pattern recognition receptors''' (PRRs) expressed on mammalian cells. These receptors are expressed on many different cell types, not just on phagocytes, though not all are expressed by all cells: different cell types express a different range of PRRs. PRRs are either intracellular, membrane-associated or soluble:

** Not all are expressed by all cells: different cell types express a different range of PRRs

*Recognition of pathogens via the cellular PRRs results in phagocytosis and inflammation

** PRRs are either intracellular, membrane-associated or soluble:

*Recognition of pathogens via the humoral PRRs results in various killing mechanisms

*** Recognition of pathogens via the cellular PRRs results in phagocytosis and inflammation

*** Recognition of pathogens via the humoral PRRs results in various killing mechanisms

The engagement of PRRs by PAMPs triggers:

* Engagement of PRRs by PAMPs triggers:

* '''[[Phagocytosis|Phagocytosis]]'''

** '''Phagocytosis'''

* The expression of '''cytokines''', which brings about [[:Category:Inflammation|inflammation]] and other immune responses

** The expression of '''cytokines''', which brings about [[:Category:Inflammation|inflammation]] and other immune responses