lecture 32 - innate immunity Flashcards
What type of immune responses is the inflammatory response?
Innate
What is the overall process of the inflammatory response?
Chemical signals from tissue attract more cells, mature neutrophils enter blood from marrow, blood vessels dilate so neutrophils can squeeze through to injury
Where do mature neutrophils for the inflammatory response originate?
Bone marrow
What are the overall steps in phagocytosis?
Phagocyte adheres to pathogen, forms pseudopod that engulfs particle and forms a phagosome, phagosome fuses with lysosome to form phagolysosome to break down pathogen.
What component of a phagocyte initially engulf particles at the cell surface, and what do they form?
Pseudopods on the cell surface form phagosomes/phagocytic vesicles inside the cell.
How are phagolysosomes formed?
A lysosome fuses with a phagocytic vesicle/phagosome.
How do phagolysosomes destroy pathogens?
By using toxic compounds, an acidic environment and lysosomal enzymes
What toxic compounds do phagolysosomes use to destroy pathogens?
Reactive oxygen (hydrogen peroxide) and reactive nitrogen (nitric oxide)
What form of reactive oxygen is found in phagolysosomes?
Hydrogen peroxide
What form of reactive nitrogen is found in phagolysosomes?
Nitric oxide
Is the pH high or low in a phagolysosome?
Low (acidic)
What are the 3 classes of enzymes found in phagolysosomes?
Proteases, lipases, nucleases
What are proteases?
Enzymes that break down proteins
What type of enzyme breaks down proteins?
Proteases
What are lipases?
Enzymes that break down fats/lipids
What class of enzyme breaks down lipids/fats?
Lipases
What are nucleases?
Enzymes that break down nucleic acids (e.g. DNA)
What is the Complement cascade?
A component of the immune system that enhances the ability of anti-bodies and phagocytic cells to clear microbes and damaged cells.
What is complement?
Proteins that act in sequence to clear pathogens in the immune response.
How many major complement proteins are there?
9 - (C1-C9)
What are the 3 key roles of the complement system/cascade?
Opsonisation, chemotaxis, lysis
What is opsonisation, in terms of the complement system?
the binding and labelling of complement proteins to pathogens/antigens so they can be recognised by complement receptors on phagocytes.
What is the term for binding labelling proteins to phagocytes, in the complement system?
Opsonisation
What is chemotaxis?
A role of the complement system, which involves the recruitment and migration of phagocytes to the site of injury/inflammation
What is the term for the recruitment of phagocytes to injury site, in the complement system?
Chemotaxis
What is lysis?
The destruction of pathogen cells by rupturing the cell wall
What is the term for the rupturing of pathogen cell walls, in the complement system?
Lysis
What are the 3 complement pathways?
Classical, alternative, lectin
What is the classical complement pathway?
A pathway that triggers the complement cascade by binding a pathogen-bound antibody to complement.
What is the alternative complement pathway?
Pathogen binds complement to surface/pathogen component
What is the lectin complement pathway?
Carbohydrate components of microbes bind to complement.
What are the 3 complement pathways amplified by?
enzyme complex - C3 convertase
What are microbes coated with during opsonisation/labelling, and what does this enable?
Antibody or complement fragment C3b - allows them to be attracted to phagocytes for destruction
What is the process of destruction in the complement pathway of innate immunity?
Microbes coated with complement fragment c3b are phagocytised. Complement protein C9 allows for the assembly of membrane attack (MAC) complex creates pores that lead to lysis.
What is the process of recruitment in the complement pathway?
Phagocytes are attracted into the site of injury/infection. Mast cells are degranulated by complement proteins C3a and C5a, releasing inflammatory mediators that tract phagocytes.
What proteins degranulate mast cells in recruitment of the complement pathway?
C3a and C5a
What are inflammatory mediators?
Substances released during the degranulation of mast cells.
How does recruitment lead to the attraction of phagocytes to a site of infection?
Inflammatory mediators released from mast cells include proteins that attract phagocytes.
What is the term given for the clinging of neutrophils to capillary walls in an innate reaction to a peripheral site of early infection/inflammation?
Margination
What is the name given to the process in which mature neutrophils are released from bone marrow to facilitate an immune response?
leukocytosis
What is diapedesis?
When neutrophils travelling to an inflammatory response squeeze through capillary walls to exit blood stream
What complement protein leads to “destruction” via the creation of a MAC?
C9
What is the function of C3 convertase enzyme?
Breaks C3 complement protein into C3a and C3b
