Innate Immune Protection Flashcards
(27 cards)
What are the characteristics of the innate immune response?
first line of defence born with it very fast responds the same every time induces adaptive immunity
What are the physical barriers of the innate immune response?
skin, gi tract, respiratory tract, mucosal epithelia
What are the 3 components of the innate immune system?
Physical/anatomical barriers
secreted compounds
cellular components
How does the skin protect against E.coli?
It produces antimicrobial compounds
What are the defence mechanisms of the respiratory tract?
tight so difficult to penetrate
has cilia to move bacteria
mucus can trap bacteria
How does the GI tract defend against bacteria?
peristalsis to move bacteria
hydrochloric acid and low pH kill bacteria
How do the eyes protect against bacteria?
By blinking and producing tears
tears, sweat and saliva contain lysoszymes which destroy bacteria walls
What is microbial competition?
The body already has lots of healthy bacteria which compete with the pathogenic bacteria for nutrients
What are PAMPs
They are pathogen associated molecular patterns which are present on microorganisms but not the hosts
What 4 things allow you to recognise bacteria?
Pattern recognition receptors (PRR)
Collectins (serum)
Toll like receptors (membrane)
Nod like receptors (cytoplasm)
What are collectins?
Made up of a collagen and lectin region
binds to sugar molecules on the surface of pathogen and affects the sugar spacing which determines whether PRR binding can occur and signal to the rest of the immune system
Features of toll like receptors?
10 of them
TLR3 - recognise RNA virus
TLR5 - recognise flagellin (in flagellum)
TLR9 - recognise unmethylated DNA (all human DNA is myelinated
They cover the cell surface
Features of nod like receptors?
Sit in cytoplasm
recognise gram positive and gram negative bacteria
NOD 1 = sense y-glutamyl diaminopimelic acid
NOD 2 = sense muramyl dipeptide
What are compliments?
A series of proteins which operate via a cascade
uses protein C3 activated by C3 convertase
What are the two molecules involved in phagocytosis?
Macrophage
Neutrophil
What are the 7 steps of phagocytosis?
1) chemotaxis and adherence of microbe to phagocyte
2) ingestion of microbe by phagocyte
3) formation of a phagosome
4) Fusion of the phagosome with a lysosome to form a phagolysosome
5) digestion of ingested microbe by enzymes
6) formation of residual body containing indigestible material
7) discharge of waste material
How does the phagolysosome?
Production of reactive oxygen intermediates and by the production of reactive nitrogen intermediates
What is the respiratory burst?
following phagocytosis there is an increase in oxygen uptake
oxygen is reduced by NADPH oxidase to form hydroxyl radicals and hypochlorite
reactive oxygen intermediates cause DNA damage and alterations in bacterial membranes
How does nitrogen intermediates cause death?
Produces DNA damage and alterations in bacterial membranes
What are cytokines?
They are proteins and intracellular messengers
What are chemokines?
promotes inflammation by enabling cells to adhere to the surface of blood vessels and migrate to infected tissue
What do type 1 interferons do?
They activated NK cells, they kill virally infected cells and tumour cells, they are responsive to TNFa and IL-12 and they produce IFNy
What are critical cytokines?
Activates macrophages and upregulates MHC molecules together with IL-12. stimulates differentiation of CD4 th1 cells
How the innate immunity moves to the adaptive immune response?
Naive T-cells activated by 2 signals
1 - antigen presenting cell to the t cell from small fragments as well as MHC
2 - Innate immune response generates second signal by recognition of pathogens by PRR’s
T-cells then become the effector t-cell
Upon recognition of pathogen by a TLR, cytokines can be produced and effect the t-cell
