Module 3: Immunological system Flashcards
What are the major cells in the 1st line of defence (barrier)?
Epithelial cells and microbiome
What are the major cells involved in the 2nd line of defence (innate immunity)?
Mast cells, neutrophils, macrophages, NK cells
What are the major cells involved in the 3rd line of defence (adaptive immunity)?
Dendritic cells, T & B lymphocytes
What are the chemical mediators involved in the 1st line of defence (barrier)?
Defensins, cathelicidins and bacterial toxins
What are the chemical mediators involved in the 2nd line of defence (innate immunity)?
Complement proteins, cytokines, kinin & clotting factors
What are the chemical mediators involved in the 3rd line of defence (adaptive immunity)?
antibodies, complement proteins and cytokines
What is the role of defensins?
Break bacterial membranes. Can activate innate and adaptive immune cells
What is the role of cathelicidins?
Insert and form pores in bacterial membrane. Released by many epithelial cells
What are the benefits of mutualistic bacteria and fungi?
- Producing enzymes that aid in digestion, useful metabolites (vit K/B), and antibacterial factors to prevent infection
- Compete with pathogens for nutrients and space to grow
- Helps train the adaptive immune system
What are the 4 major benefits of inflammation?
1: prevents further damage and infection by invading pathogen
2: prevent the inflammatory process from reaching healthy sites
3: coordinates with the adaptive system
4: prepares the injured area for healing and repair
What are the 5 cardinals signs to local inflammation?
Redness, swelling, heat, pain and partial loss of function
What are the systemic manifestations of inflammation?
Fever, leukocytosis and plasma protein synthesis
What triggers fever?
Pyrogens (IL-1)
What is leukocytosis?
An increase in circulating white blood cells due to an inflammation response
What triggers plasma protein synthesis?
IL-6
Where are plasma proteins mostly synthetised?
In the liver
Name 3 acute-phase reactants in the plasma protein synthesis.
Fibrinogen, Complements and C-reactive protein (CRP)
What is the role of mast cells?
Once they are activated by other chemicals or antibodies, they degranulate and release histamine into the bloodstream, which promotes vasodilation. they also attract neutrophils with a neutrophil chemotactic factor. they release cytokines that promote inflammation
What are cytokines?
Small intercellular signalling molecules, either pro or anti-inflammatory
What are interlukins? (IL)
- Major class of cytokines, mainly produced by macrophages
What are interferons? (IFN)
- Family of cytokines specifically efficient against viral infections
- IFN a&b released by infected cells
- IFN-y released by lymphocytes
What are chemokines?
Cytokines that specifically act as honing signals, attracting immune cells to sites of injury (chemotaxis)
What is the main action of TNF-a?
- Pro-inflammatory
- Systemic inflammation manifestations
- Synthesis and release of IL-1
- Potentially fatal if released in excessive amounts = sepsis
What is the main action of IL-1?
- Pro-inflammatory
- endogenous pyrogen = fever
- activation of neutrophils, macrophages, lymphocytes
- diapedesis of phagocytes
What is the main action of IL-6?
- Pro-inflammatory
- Stimulate the liver to synthesize acute-phase reactants
- proliferation of fibroblasts for wound healing
What is the main action of IL-8?
- Pro-inflammatory
- Chemotaxis
What is the main action of IL-10?
- Anti-inflammatory
- Down-regulates the immune response
What is the role of TGF-b?
- Anti-inflammatory
- promote blood cell maturation to replenish used up cells
What are the 3 activation pathways for the complement system?
- Classical
- Alternative
- Lectin
What are the 2 activation pathways for the clotting system?
- Tissue factor (extrinsic)
- Contact (intrinsic)
What are the functions of the kinin system?
- Activates and assists inflammatory cells
- Primary kinin is bradykinin
- Causes the following: dilation of blood vessels, smooth muscle contraction, induces pain, increases vascular permeability
What are neutrophils?
- most common WBC
- first one on site of injury
- pus/exudate = dead pathogens and neutrophils
What are macrophages?
- most efficient and resistant phagocytes
M1= bacterial cleaning
M2 = wound healing/cleaning/repair - adaptive immunity activation