Lecture 7: Innate Immunity Flashcards
What are the fundamentals of the innate immune response?
Non-specific immune response by immune cells recognise antigen through non-specific pattern recognition receptors which are ‘germline encoded’.
What are the functions of the innate immune response?
- Prevents infection
- Promotes acute inflammation
- Responds rapidly
What are some of the features of the innate immune response?
Physical and mechanical barriers such as skin and expulsive reflexes of the lungs and nose (coughing and sneezing to remove foreign particles). Chemical barriers such as stomach pH and salivary enzymes. Microbiological barriers such as the normal bodily flora.
What are the receptors of the innate immune response?
Pattern recognition receptors (PRRs); detect antigens non-specifically
What do innate immune cell receptors look for during infection?
Pathogen-Associated Molecular Patterns (PAMPS).
What is phagocytosis?
Phagocytosis is the process of engulfing and killing foreign cells. Process triggers activation of inflammation by soluble mediators and also antigen presentation.
How does phagocytosis trigger local inflammation?
Phagocytosis activates release of soluble mediators such as cytokines ( eg. TNF-alpha, IL-1, and IL-6) and chemokines (eg. CXCL8) which promote local inflammation by attracting other immune cells and act on blood vessels to trigger vasodilation and increased permeability.
What are some examples of cytokines?
TNF-alpha, IL-1 and IL-6
What are some examples of chemokines?
CXCL8
What is complement?
A circulating component of innate immunity. Complement is a series of enzymes that result in a MAC (membrane attack complex; terminal pathway) which generates a pore in pathogen membrane that leads to cell lysis.
Where is complement found and formed?
Complement is a series of enzymes that circulate in the bloodstream in their inactive form and are produced in the liver.
What are the 3 pathways of complement activation?
- Classical pathway
- Mannan-binding lectin pathway
- Alternative pathway (bacteria directly activates complement on its surface).
How does complement play a role in opsonisation?
Activated complement component C3b sticks to pathogens and this facilitates binding to phagocyte C3b receptors to promote phagocytosis.
What is opsonisation?
Marking of antigen for phagocytosis by immune cells
What is the role of alpha interferon in viral infections?
Alpha interferon is a soluble innate mediator that is activated by viral infection and it stops viral cell division, stops viral cells synthesising new proteins, and stimulates production of anti-viral proteins by host cell.
