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immunology Flashcards

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1
Q

Describe the properties of the skin as a physical barrier to infection

A

It is constantly renewed
It has a low pH
It has a low oxygen tension
Sebaceous glands secrete hydrophobic oil which makes it hard for pathogens to bind

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2
Q

Mucous line all _____ that come into contact with the _______

A

Body cavities

Environment

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3
Q

Mucous contains many constitutes which can fight potential pathogens, what are these?

A 
Secretory IgA
Lysozymes
Defensins
Antimicrobial peptides
Lactoferrin- starve induing bacteria of iron
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4
Q

What are commensal bacteria?

A

Bacteria that reside in the body and on epithelial surfaces naturally
They have a symbiotic relationship with the body and can eradicate most normally infections
They ensure there is no undefended ecological niche

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5
Q

The components of the immune system can be split into which two categories?

A
  1. Cells

2. Humoral immunity (soluble factors)

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6
Q

Which 3 main groups of cells are involved in the immune system?

A
  1. Phagocytes
  2. Lymphocytes
  3. Granular
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7
Q

When a cell is infected with a virus what will it secrete?

A

Interferons (alpha and beta)

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8
Q

The antiviral state initiated by interferons achieve what?

A

It down regulates protein synthesis which slows virus production

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9
Q

What is an antigen?

A

A substance able to stimulate an adaptive immune response- it can be protein, carbohydrate, nucleic acid, lipid, metal etc

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10
Q

Where are T and B cells formed?

A

Bone marrow

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11
Q

Where do B cells mature?

A

Bone marrow

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12
Q

Where do T cells mature?

A

Thymus gland

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13
Q

In response to an infection B cells will produce what?

A

Antibodies and memory cells

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14
Q

What are the two types of T cells?

A

Helper T cell (CD4+)

Cytotoxic T cells (CD8+)

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15
Q

How does a virus evade the immune system?

A

It will usually hide within body cells

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16
Q

How can cytotoxic T cells discover viruses hiding in the body cells?

A 
The host cell constantly samples its cytoplasm and displays proteins on its surface- this is mediated by MHC class 1 proteins 
These displayed proteins can "show" cytotoxic T cells which cells are infected
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17
Q

How do viruses evade the process of cytoplasm sampling mediated by MHC class I proteins?

A

They down regulate the production of MHC class I proteins. This reduced cytoplasm sampling

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18
Q

How do natural killer (NK) cells retaliate to viruses that down regulated MHC class I production ?

A 
NK cells can detect a lack of MHC class I proteins on a cell surface
They can then attack and destroys such cells
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19
Q

How are parasitic works (helminths) attacked by the immune system?

A

Antibodies and mast cells

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20
Q

What is the complement system and where is it produced?

A

Family of around 30 different proteins produced in the liver

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21
Q

How does the complement system function?

A

When activated, the proteins activate each other in a. cascade fashion
This involves great amplification and plays a role in inflammation

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22
Q

When do monocytes differentiated into macrophages?

A

When they exit the blood and migrate to peripheral tissues

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23
Q

What are Kupffer cells?

Study These Flashcards
A

Macrophages of the liver

24
Q

What are mesangial cells?

Study These Flashcards
A

Macrophages of the kidney

25
What are macrophages of the nervous system called?
Microglia
26
How can neutrophils be differentiated from macrophages ?
Their multi-lobed nucleus
27
What is the role dendrite cells?
They engulf pathogens, phagocytose and then present antigens on their surface to T cells
28
What are the main functions of neutrophils?
Killing and degradation
29
What are the main functions of macrophages?
Killing, degradation, wound healing, anti-inflammatory and antigen presentation
30
What is the main function of dendrite cells?
Antigen presentation
31
What is lymphodema and why may it result in infection?
It's a condition characterised by a lack of draining of tissue fluid by the lymphatic system. The fluid builds up and is not cleaned as effectively leading, potentially, to infection
32
The immune system itself is composed of two halves- what are these halves and how are they connected?
1. Innate immune system 2. Adaptive immune system Joined through the action of dendritic cells
33
What is meant by "direct contact" between immune cells and pathogens?
A receptor/ ligand interaction
34
What is meant by "indirect contact" in the immune system ?
Communication between cells and pathogens through the use of cytokines
35
What are autocrine signals?
Signals produced by a cell that lead to self-activate
36
Interferons have the role of activating an _____ _______
Antiviral state
37
Which cells may secrete interferons?
Infected cells
38
Release of interferons has two main outcomes, what are they?
1. Protein synthesis is downregulated 2. Employment of particular molecules into the cell membrane is upregulated such as MHC class I- allows for detection Interferons can also instruct cells to undergo apoptosis
39
What are the signs of acute inflammation?
- redness- vasodilation - swelling- vascular permeability - heat- high metabolic function - pain - loss of function
40
What are the three phases of the innate response?
1. Recognition 2. Activation 3. Effector
41
Describe recognition as a phase in the innate response
Innate immune cells recognise pathogens due to the expression of PAMPs which bind to PRR on innate immune cells
42
What are PAMPs?
Pathogen associated molecules patterns | These are ligands expressed on the surface of pathogens which allow them to be detected by immune cells
43
What are PRRs?
Pattern recognition receptors | Found on innate immune cells that are receptors for PAMPs found on pathogen
44
How do macrophages differentiate between apoptotic cells and normal cells?
Normally phospholipids called phosphatidlyserine are held facing inward to cytoplasm by the enzyme flippase In the event of apoptosis, phosphatidlyserine is flipped to face outwards by the action of the enzyme scramblase These outward facing phophatidlyserine lipids act as signals for macrophageal engulfment
45
PAMPs have the ability to activate which three immune cells
1. Macrophages 2. Mast cells 3. NK cells
46
Injured cells release which type of signals?
Danger signals (e.g. IL 33 )
47
What happens when macrophages cannot kill a pathogen?
Infected macrophages are walled off forming Granulomas | The purpose of this is to prevent the spread of infection
48
What will be present on the surface of macrophages afar engulfment of pathogen?
Fragments of pathogen protein | This allows for recognition by antigen presentation
49
Interferon gamma can cause what change in a macrophage?
It will cause super activation This allows for expression of inducible nitric oxide synthase- an enzyme allowing for production of toxic oxygen and nitrogen species The antigen presentation capacity of macrophages will also increase
50
What are mast cells found most prominently?
Mucosal surfaces
51
Which two processes occur when a PRR on a mast cell is bound by a PAMP?
- Degranulation - release of pre-formed pro-inflammatory mediators are released allowing for acute inflammation - Gene expression- production of new pro-inflammatory mediators commences within mast cells
52
Why do NK cells not kill normal healthy cells?
``` Normal cells have MHC class I protein on their surface which is bound to self proteins (antigens) NK cells have a receptor on their surface that binds to the MHC class I protein and antigen When the antigen/ MHC class I combination is of self-origin, inhibitory signals are sent to the NK cells ```
53
How do viruses evade cytotoxic T cell killing?
They cannot be detected by the antigen/MHC class I receptor system because they downregulate MHC class I production meaning it is more difficult for foreign antigens to be "seen"
54
How do NK cells kill cells in which viruses have down regulated MHC class I production/
``` If no ligand (MHC class I +antigen) is present, NK cells cannot be inhibited so the cell is killed regardless NK cells take no chances ```
55
Upon activation NK cells secrete pro inflammatory mediators such as _____ gamma
Interferon

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