Immune System Overview Flashcards
What is the purpose of the immune system?
Maintain tissue homoestasis through:
- Encouraging tissue healing
- Tissue surveillance
What are the main components of the immune system?
PHYSICAL AND CHEMICAL BARRIER
- skin
- mucosa in resp, GI and urinart tracts
- chemical barriers i.e. HCL acid in stomach and lysozymes in sweat/tears
INITIAL RESPONSE
- complement
- Macrophages-> active innate immune system
- Dendritic (APC)-> activate adaptive immune system
INNATE SYSTEM
- macrophages
- Inferons + cytokins
- Inflammation + acute phase response
- NK cells
ADAPTIVE SYSTEM
- Dendritic cells
- CD4->TH cells
- CD8->cytotoxic cells
- B cells-> plasma cells or memory cells
What are the components of the complement system and what roles do they have in response to a pathogen?
-Membrane Attack Complex (MAC) formed from terminal components to destroy the pathogen
C3b= opsonization i.e. marking pathogen for phagocytosis
C5a= attracts neutrophils, monocytres and eosinophils
C3a/4a/5a= activate mast cell degranulation
C3a/5a= activate eosinophil degranulation
What roles do macrophages have as part of the innate immune response?
Phagocytosis
Release cytokines
- recruit monocytes to become macrophages
- activates more macrophages
- recruits neutrophils
- initiate inflammatory response
- activates mast cell degranulation
- activates clotting system activation
Release interferons
-inhibits viral entry and replication within cells
What is an acute phase response? What happens during an acute phase response?
What are the key signs on acute inflammatory response?
Neutrophil influx
Complement activation
Histamine release= increased vasodilation + permeability
Inflammation which triggers neutrophils and macrophages to release interleukins
- IL-1= fever/lethargy/anorexia
- IL-6= liver produces acute phase proteins
- IL-8= recruits + activations neutrophils
- IL-2 + IL-12= activates NK cells
- TNF-alpha= all above
What is the role of NK cells in innate response?
Kill virally infected and tumour cells
Produce INF-gamma to stim macrophages
What cells are involved in the adaptive immune response and how do they interact?
Dendritic cells
- present antigens via MHC 1 to CD4 TC
- release co-stimulatory molecules
TH cells
-formed from CD4 cells
-activated CD8 cells to become cytotoxic TC
-activate BC
-activate macrophages
I.e. activation occurs via cytokine production
Cytotoxic TC
-destroy infected cells via cytokines and activation of Fas molecules
BC
- become plasma cell -> secrete antibodies
- become memory B cells -> activated on subsequent infection
What are the 1st lines of defence to infection in the respiratory + GIT systems?
RESP:
muco-ciliary escalator
-moves mucus up the phalynx in order to be swllaowed
Anti-microbial peptides (defensins)
-produced by cilia
GIT:
-HCL
Why can smoking infection the risk of infections?
Paralysis the cilia in the respiratory tract leading to mucus not being cleared
What are the ways which the primary immune defence barriers can be disrupted?
PHYSICAL
- IV access devices
- catheters
- burns
- skin ulceration
PHARMACOLOGICAL
- PPI
- Anti-cholinergics i.e. reduces saliva production and can cause urinary retention (increased risk of urinary infection)
Which cytokines and organs are involved with the different parts of the acute inflammatory response?
Hypothalamus
- IL-1 + IL-6
- fever/rigors/anorexia
Liver
- TNF-alpha + IL-1 +IL-6
- acute phase response proteins i.e. CRP, complement, transferrin, fibrinogen, SAA
Bone marrow
- TNF-alpha + IL-1 + IL-6
- increased mobilisation
Fat + muscle
- TNF-alpha + IL-1 + IL-6
- metabolism change i.e. protein breakdown + cachexia
What can be used to monitor the acute phase response?
Measure acute phase response proteins
I.e. C-reactive protein (opsonin)
