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POM > immune response to infection > Flashcards

immune response to infection Flashcards

1
Q
  • What are innate immune responses mediated by?
A

Complement

Phagocytes (neutrophil, NK, DC)

Natural killer
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2
Q
  • What are the 2 general phases of an immune response?
A

Antigen recognition - clonal selection leading to clonal expansion of specific clones of T and B cells and differentiation to effector and memory cells

Antigen eradication - lymphocytes coordinate immune response
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3
Q
  • What are the 4 types of pathogen niches during infection?
A

Extracellular

Intracellular vacuolar

Surface adherent

Intracellular cytosolic
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4
Q
  • List some examples of pathogens which are extracellular
A

Staphylococcus

Streptococcus 

Candida 

Worms
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5
Q
  • Explain how an immune response begins?
A

Tissue damage (cut, toxins produced etc.)

Microbes that shouldn't be there are detected 

Communication between cells (e.g. through interleukins and chemokines)

This leads to the priming of the adaptive immune response
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6
Q
  • How does an immune response come to an end?
A

Infection cleared

Stopping inflammatory cytokine production 

Repairing tissue damage (macrophages and phagocytic cells)

Immune memory
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7
Q
  • What are the differences between innate and adaptive immunity?
A

Innate- Fast acting, First line of defence, Germline encoded receptors

Adaptive, Slower but long lasting, variable receptors that mature over time

Also innate provides physical barriers whereas adaptive doesn't.
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8
Q
  • Give examples of physical barriers provided by innate immunity
  • Is complement part of innate or adaptive immunity?
A

Skin, mucous, epithelial cells

It's actually present in both
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9
Q
  • What are the key cellular components of innate immunity?

- What are the key cellular components of adaptive immunity?

A

Neutrophils, macrophages, dendritic cells and natural killer (NK) cells

Cytotoxic T-cells, T helper cells, T regulatory cells, B lymphocytes and plasma cells
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10
Q
  • What is the difference in specificity between innate and adaptive?
A

Innate is less specific than adaptive as innate detects broad classes of pathogens such as all gram positive bacteria (e.g. cell membrane components such as peptidoglycan) or PAMPS (pathogen associated molecular patterns) from different microbes

whereas adaptive can detect structural detail of antigens and may even recognise non-microbial antigens eg diphtheria toxin

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11
Q
  • What are the differences between innate and adaptive immunity receptors?
A

Innate immune receptors don’t vary (have a limited diversity) whereas adaptive immune receptors have a much greater diversity

innate only have four types of receptor (inc toll-like)
adaptive only two types ( TCR and Ig)

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12
Q
  • Why is there a greater diversity in adaptive immune receptors in comparison to innate immune receptors?
A

Adaptive immune receptors are encoded by genes produced by somatic recombination hence they produce TCRs and Ig’s that have millions of different variations

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13
Q

How do immune cells alert those around it after infection?

A

Microbial molecules detected

Naïve host-cells are changed - gene expression leads to their activation

Production of antimicrobial molecules which send communication signals to alert neighbouring cells (autocrine and paracrine effects)

Leads to the production of activated and specialised host cells
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14
Q
  • What are the first responders at the site of injury?

- What can uncontrolled activities of these first responders lead to?

A

Neutrophils (short-lived, ~6 hours) followed by macrophages

Naive immune cells become activated upon interaction with microbes

Granulomas, Excessive inflammation, Tissue damage

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15
Q
  • What genes have an increase in expression due to bacterial exposure?
A

Release of cytokine (e.g. IL-1 beta - fever)

Anti-microbial genes (directly toxic to bacterial pathogen)

Metabolic gene 

Immunomodulatory gene
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16
Q
  • What does recognition of a fungi lead to?
A

Proinflammatory response (different to that of bacterial)

Antimicrobial genes, metabolic genes and immunomodulatory genes which all cope with fungal infections
17
Q
  • What molecules interfere with viral replication?

- What kind of genes regulate an inflammatory response to an infection?

A

Interferons

Antiviral genes and immunomodulatory genes
18
Q
  • What do activated macrophages display?
A

Enhanced:

Phagocytosis and migration 
Cytokine/chemokine production 
Expression of cell surface molecules 
Antimicrobial activity 
Antigen presentation and T cell activation
19
Q
  • What results in the production of interferons?
  • What type of interferon is IFN-gamma?
  • What does type 1 (IFN alpha/beta) interferon signalling lead to?
A

Detection of viruses and gram-negative bacteria

Type 2 - only produced by lymphocytes and promotes antibacterial immunity

Expression of a number of antiviral genes
20
Q
  • What do antiviral genes include?
A

Nucleases

Inhibitors of virus entry and exit 

Inhibitors of viral uncoating and replication

Inhibitors of protein translation
21
Q
  • Where can type 3 IFNs be produced?

- What type of cells produce IFN-gamma?

A

Only produced at epithelial surfaces whereas type 1 can be produced deeper in tissues

Only produced by lymphocytes
22
Q
  • What does cell death remove?
  • Give 2 antimicrobial enzymes that are produced by a cytokine binding to a cytokine receptor leading to the killing of microbes?
A

Viral replicative niches

Phagocyte oxidase - produces reactive oxygen species (ROS)

Inducible nitric oxide synthase - produces nitric oxide (another radical that is highly toxic to intracellular pathogens)
23
Q
  • What do type 1 and 3 interferons promote?

- What type of cell is more specialised in presenting antigens between macrophages and dendritic cells?

A

Antiviral responses

Dendritic cells (also able to respond to viral infections much better because they can produce a lot of type I interferon during infection)
24
Q
  • Outline the process of T cell activation by dendritic cells?
A

Activated DCs present antigens in combination with MHC-1 or MHC-2 to T cells

Naive T cells activated by cytokines (**IL-12, TNF)** produced by antigen presenting cells 

**T cells provide cytokines (e.g. IFN-gamma and IL-17) which further activates the presenting cell**

T cell then differentiates into a specific type according to general class of pathogen (i.e. what type of pathogen is present)
25
Q
  • In what infections are Th1 (T helper cells) normally produced and what is the outcome?
  • What type of T cells are typically produced during viral infections?
A

Intracellular bacterial infections
Leads to inflammation, phagocytosis and killing of microbes

Cytotoxic T cell (CD8) - killing of infected cell (apoptosis of host cells and removal of the replicative niches)
26
Q
  • List the broad functions of T cells?
A

Phagocyte activation - enhance killing of pathogen, kill immune cells

Direct killing of infected cells - removing replicative niches 

B cell activation - antibody production and affinity maturation

Innate lymphoid T cells - type of early responders (MHC independent actions)
27
Q
  • To which pathogens are Th17 made?
  • To which pathogens are Th1 made?
  • To which pathogens are Th2 made?
A

extracellular Bacteria, Fungi

intracellular pathogens- Bacteria, Protozoa

Helminth, Allergens, Venoms
28
Q
  • What is the role of a first responder?
A

To detect infection and try to control microbial growth and spread

29
Q
  • What kind of genetic dysfunction leads to chronic granulomatous disease?
  • What kind of genetic dysfunction leads to Chediak-Higashi syndrome?
A

Loss of reactive oxygen species production

Compromised lysosomes

30
Q
  • A genetic dysfunction in the genes controlling what leads Severe Combined Immunodeficiency (SCID)?
  • What genetic disfunction leads to X-linked aggamaglobulinaemia?

]

A

Severe reduction and function of T and B cells

Decreased serum IgG of all types

31
Q
  • On average, how long after infection will it be until the adaptive immunity system begins?
A

12 hours

POM (47 decks)

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