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Infection, immunity and repair > Cells of the innate immune system > Flashcards

Cells of the innate immune system Flashcards

1
Q

What are the characteristics of the innate immune response?

A

Broadly specific

Doesn’t show immunological memory

Immediate

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2
Q

The immune system comes into play in most cases

TRUE or FALSE

A

FALSE

Most cases the immune system does not come into play since immunological barriers are very effective

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3
Q

Which cell gives rise to the innate immune cells?

A

Myeloid progenitor

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4
Q

What developmental pathway gives rise to the adaptive immune cells?

A

Myeloid developmental pathway

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5
Q

Where are Neutrophils found?

A

IN the blood and tissues

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6
Q

Where are Monocytes found?

A

In the blood

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7
Q

Where are Macrophages found?

A

IN the tissues

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8
Q

Where are Dendritic cells found?

A

In the tissues

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9
Q

Where are eosinophils found?

A

In the blood and tissues

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10
Q

Where are mast cells found?

A

In the mucosa and connective tissue

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11
Q

Where are basophils found?

A

In the blood

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12
Q

Where are natural killer cells found?

A

In the blood and tissues

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13
Q

Which cells are phagocytic?

A

Macrophages, monocytes, Dendritic cells and Neutrophils

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14
Q

Which cell is phagocytic and promotes inflammation?

A

Eosinophil

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15
Q

Which cells promote inflammation?

A

Mast cells and Basophils

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16
Q

Which cell kills virus infected cells?

A

Natural killer cells

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17
Q

Which types of cells does the myeloid progenitor give rise to?

A 
Megakaryocytes 
Erythrocytes 
Dendritic cells 
Monocytes 
Leukocytes
18
Q

What is a distinguishing feature of Natural Killer cells?

A

Form part of the innate immune system

But originate from the lymphoid progenitor cell

19
Q

What are the 3 sentinel cells?

A

Neutrophils - in blood, migrate to tissue in response to infection = short lived

Monocytes - leave blood to form macrophages, live longer

Dendritic cells - many different cell types

20
Q

Describe the process of phagocytosis

A

Chemotactic gradient attracts phagocyte to the zone of infection

Phagocytic cell comes into contact with pathogen

CSM recognition structure recognises structures of the infectious agent

PAMPs on pathogens bind to PRRs on phagocytic cells - adherence

Phagocytic cells activate via signals sent from the PRRs

Phagocytic cells release pseudopodia and engulf the pathogen

Pseudopodia fuse to form a vacuole and trap the pathogen - phagosome

Lysosomes move towards and fuse with phagocome to release lysozyme

This forms a phagolysosome

Lysosomes contain substances that destroy the trapped microbe

Release of degradation products

21
Q

What are the ways in which the phagolysosome kills a pathogen

A

Oxidative killing - reactive oxygen species

Nitric oxide-related killing - reactive oxygen intermediates

Non-oxidative killing mechanisms - lysozyme breaks down the bacterial cell wall

22
Q

What is the inflammatory response?

A

Process by which the phagocytic cell enters the zone of infection

Blood is the transport system - inflammatory mediators are released here to let cells know about the infection, so they can move from the blood into the tissues

23
Q

What are the two inflammatory mediators used in the inflammatory response?

A

Inflammatory chemicals - histamines released by mast cells and basophils

Lipopolysaccharides - released by gram negative bacteria

24
Q

Describe the process of the inflammatory response

A

Molecules are expressed which are not normally expressed

This leads to upregulation of P-selectin on vascular endothelium

Neutrophils recognise P-selectin by PSGL-1

Neutrophils adhere to the vascular endothelium and stops transit through blood

Neutrophils and vascular endothelium express adhsion molecules

Adhesion molecules released by the endothelium recognise those released by neutrophils = stronger adhesion

Neutrophils squeezes in between endothelial cells -> diapedesis

25
Q

What adhesion molecules are expressed by the vascular endothelium and neutrophils?

A

Integrin

ICAM-1

E-selectin

26
Q

What is diapedesis?

A

Process by which neutrophils squeeze in between endothelial cells

27
Q

What is the role of eosinophils?

A

Phagocytic - not main job

Deals with organisms too large to be engulfed

28
Q

How do eosinophils kill parasites?

A

Releases granules with toxic molecules to carry out extracellular killing

4 major molecules involved include

Major basic protein
Cationic protein
Oxygen metabolites
Perforins - punches holes in the surface of parasites

29
Q

What are the roles of basophils and mast cells?

A

Responsible for allergy

Get rid of parasitic worms in the gut

30
Q

How do mast cells and basophils do their function?

A

Work by coating in IgE - via FCE receptors that bind to Fc portions of antibodies

31
Q

How does IgE work?

A

Antigen binding part of IgE = FAB

Sticks out from the mast cell/ basophil

When antigen comes along the IgE binds and recognises it

IgE links together and activates the basophil/mast cell

Release inflammatory mediators

32
Q

What are the two types of inflammatory mediators released by mast cells/ basophils?

A

Ones that are stored in granules - histamine, serotonin

Ones that are newly synthesised - TNF-a, prostaglandin and leukotrienes

33
Q

What is immunopathology?

A

Dangerous condition where an inflammatory response is targetted against a hermless agent

Can be dangerous

34
Q

What did people think was the relationship between mast cells and basophils?

A

Mast cells = tissues

Basophils = blood

Thought that the two were related

Basophils differentiated into mast cells when moved into tissue

Wrong - both are terminally differentiated

35
Q

What is the role of the NK cells?

A

Kill as much as possible in the body

36
Q

Which two receptors are present on CSM of NK cells?

A

Activating receptor

Inhibiting receptor - specific for MHC I found on all cells

37
Q

What is MICA?

A

Protein found on the membrane of some cells that bind to the activating receptors on NK cells

38
Q

How do cells expressing MICA avoid apoptosis by NK cells?

A

MHC I on normal cells binds to inhibiting receptor on NK cells which overrides activating receptor

39
Q

How do NK cells kill abnormal cells?

A

Abnormal cells lose expression of MHC-I receptors

SO they can no longer bind to inhibitor receptors on NK cells

NK cells recognise these as being abnormal - MICA still binds to the activating receptor

Some abnormal cells can also overexpress MICA/ activating SM proteins - overrides the inhibition signal by MHC I

40
Q

Mechanisms of non-oxidative killing

A

Lysozyme
Defensins
Lactoferrin
Proteases

Infection, immunity and repair (52 decks)

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