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
What tells NK cells that they can attack a cell?
If it does not have the MHC-1 expression
After how much time do you consider inflammation to be chronic?
After more than 2 weeks
Define regeneration
replacement of injured tissue with healthy tissue. its the return to normal structure and function (healing with 1st intention)
Define repair
replacement of damaged tissue with scar tissue to fill in a lesion and restore strength. causes partial loss of function (healing with 2nd intention)
What is the result of dysfunctional collagen synthesis?
Keloids and hypertrophic scars
What is the result of ischemia in wound healing?
small vessel disease (obesity & diabetes)
What is the result of excessive bleeding during wound healing?
vascular diseases / hemophilia
What is the result of infection during wound healing?
prolonged inflammatory response
What is the result of malnutrition during wound healing?
scurvy = poor collagen synthesis
What drugs can increase the chances of wound healing dysfunctions?
Immunosuppressants, steroids & NSAIDs / tobacco smoke
What is the role of IgM?
main antibody during primary response
What is the specialty of IgD?
is mostly membrane-bound
What is the role of IgG?
main antibody for secondary response
What is the role of IgA?
main antibody for secretory immune system
What is the role of IgE?
main antibody against worms/large parasites. main culprit of allergic reactions
Which cells are associated with cellular immunity?
TNF-b, IL-2 and INF-y
Which cells are associated with the humoral response?
IL-4, IL-5, IL-6
Which cells are involved in inflammation?
IL-17, IL-21, IL-22
Which cells are involved in the suppressed immune response?
TGF-b and IL-2
Which T-helper activation is used for the humoral response?
Th2
Which T-helper activation is used for the cell-mediated response?
Th1
Which lymphocyte is used for the humoral response?
B-cells (plasma cells)
Which lymphocyte is used for the cell-mediated response?
T-cells (CD8 and cytotoxic T-cells)
What is the main mechanism of the humoral response?
Antibody secretion
What is the main mechanism of the cell-mediated response?
activation of cell death mechanisms
What is the humoral response most effective against?
Extracellular pathogens (bacteria, viruses (pre-entry), parasites and worms
What is the cell-mediated response most effective against?
Intracellular pathogens (viruses (post-entry) or cancer surveillance
What results in a B-cell deficiency?
decrease in circulating Ig, increase in susceptibility to infections
What results in a T-cell deficiency?
DiGeorge syndrome (lack of thymus)
chronic candidiasis
Name the mechanism in every type of hypersensitivity reaction
1: IgE-Mediated
2: Tissue-specific
3: immune complex-mediated
4: cell-mediated
What allergy/environmental antigens could trigger hypersensitivity reactions?
1: hay fever, bee stings and asthma
2: drug-induced hemolysis
3: Celiac’s disease
4: Poison Ivy
What autoimmunity/self-antigen can trigger hypersensitivity reactions?
1: none
2: hemolytic anemia
3: systemic lupus erythematosus
4: Hashimoto’s disease
What alloimmunity (other human’s antigen) can trigger hypersensitivity reactions?
1: none
2: hemolytic anemia
3: anaphylaxis to IaG
4: graft rejection
Most auto-immune disorders affect more males or females?
Females because of frequent genetic predispositions
Which Igs are involved in each hypersensitivity reaction?
1: IgE
2: IgG and IgM
3: IgG and IgM
4: none
What are the major effector cells in each hypersensitivity reaction?
1: mast cells
2: tissue macrophages
3: neutrophils
4: lymphocytes and macrophages
What are the major symptoms of SLE?
- Vasculitis
- Kidney glomerulonephritis
- arthritis
- photosensitivity (discoid rash)
What causes graft transplant rejection (GvHD)?
genetic variability in MHC proteins (haplotype)
What are the characteristics of hyperacute GvHD?
- immediate and rare
- graft turns white
- preexisting antibodies to HLA antigens
- type II hypersensitivity
What are the characteristics of acute GvHD?
- days to months
- cell-mediated (type IV)
- more common
What are the characteristics of chronic GvHD?
- months to years
- progressive organ failure
- weaker delayed type IV hypersensitivity
Explain the details of the portal of entry infection property
route of transmission (inhalation, ingestion, human or zoonotic contact)
Explain the details of the communicability infection property
ability of the microorganism to spread between individuals. depends heavily on portal of entry (measles=high, HIV=low)
Explain the details of the infectivity infection property
ability of pathogens to invade and multiply within host (herpes simplex virus immune evasion)
Explain the details of the virulence infection property
the ability of viruses to cause severe disease( measles=low, ebola=high)
Explain the details of the toxigenicity infection property
the ability of bacteria and parasites to cause severe disease via the production of exotoxins and endotoxins
Explain the details of the pathogenicity infection property
the overall ability of pathogen to produce an infectious disease based on its communicability, infectivity & virulence/toxigenicity
What is an antigenic drift?
minor gradual changes via mutation accumulation
What is antigenic shift?
major sudden transformation via the exchange of whole genetic segments
