Cells of the Immune System Flashcards

1
Q

What are the two soluble factors of innate immunity?

A

Antibacterial factors

Complement system

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2
Q

What is a cellular factor of innate immunity?

A

Scavenger phagocytes

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3
Q

What are two types of antibacterial factors?

A

Lysozymes

Lactoferrin

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4
Q

How to lysozymes work as part of innate immunity?

A

Present at mucosal surfaces

Active in breaking down the gram positive cell wall of bacteria

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5
Q

How does lactoferrin work as part of innate immunity?

A

Present at mucosal surfaces

Binds free iron and therefore reduces soluble iron in the GI/respiratory tract to inhibit bacterial growth

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6
Q

What are the three final pathways of the complement system?

A

Opsonisation of pathogens
Recruitment of inflammatory cells
Killing of pathogens

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7
Q

What are the two functions of macrophages in immunity?

A

Clearance of microorganisms

Recruitment of help from other cells e.g. lymphocytes

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8
Q

What are macrophages (tissue) derived from?

A

Monocytes (blood)

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9
Q

What are the three main roles of macrophages?

A

Phagocytosis

Antigen presentation - presents to T cells in MHC II

Cytokine production

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10
Q

What is the role of pattern recognition receptors?

A

Recognises extracellular and intracellular threats to produce a response

Responds to bacteria, yeasts and fungi by releasing interleukin-1beta and TNF-a

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11
Q

Why may innate immunity not always be enough? (2)

A
  1. Highly pathogenic bacteria which can evade immune response
  2. Structural failure - e.g. wounds
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12
Q

What percentage of white blood cells is composed of neutrophils?

A

50-70%

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13
Q

What are the main roles of neutrophils? (4)

A

Chemotaxis
Phagocytosis - uses proteases, ROS, lysozymes etc
Degranulation - toxic
Die locally - produces pus

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14
Q

What percentage of white blood cells is composed of eosinophils?

A

1-6%

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15
Q

What to eosinophils usually respond to in immunity?

A

Parasites

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16
Q

What pathological mechanism can be caused by eosinophils?

A

Allergy

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17
Q

What are the main roles of eosinophils? (3)

A

Chemotaxis - in response to chemokines

Degranulation - releases toxins onto surface of parasites

Cytokine production - drives inflammation

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18
Q

What sites to mast cells guard?

A

Mucosal sites

19
Q

What are the two main roles of basophils (blood) and mast cells (tissue)

A

Degranulation - rapid release of PREFORMED granules e.g. histamine - wheal and flare reaction

Cytokine release - stores many preformed cytokines that attract and drive subsequent immune response

20
Q

Where are dendritic cells derived from?

A

Monocytes - same as macrophages

21
Q

What are the main functions of dendritic cells? (3)

A

ANTIGEN PRESENTATION - can initiate the adaptive immune response

Phagocytosis

Migration - constantly sampling environment. Travels to draining lymph nodes when activated

22
Q

What is the role of the Fc region on antibodies?

A

Binds to Fc receptors on phagocytes

Activates complement

23
Q

What are the three main roles of antibodies?

A

Opsonise for phagocytosis

Activate complement system

Neutralise toxins and pathogen binding sites

24
Q

What is the main antibody isotype of the primary immune response?

A

IgM

25
Q

What is the main antibody isotype of the secondary immune response?

A

IgG

26
Q

What is the difference between IgM and IgG antibodies in terms of affinity?

A

IgM lower affinity than IgG

27
Q

Which antibody can cross the placenta?

A

IgG

28
Q

Which antibody acts as an antiseptic paint by being present in secretions and epithelial surfaces? How does it carry out an immune response?

A

IgA

Neutralises by blocking the binding of pathogens

29
Q

What is the role of IgE in immunity?

A

High affinity
Binds to mast cells through the Fce receptor

Also has a role in allergy

30
Q

What are the 4 processes which can take place after clonal expansion of activated B cells?

A
  1. Antibody secretion (IgM)
  2. Isotype switching (from IgM to IgG)
  3. Affinity maturation (high affinity IgG)
  4. Memory B cell
31
Q

In what ways do T cells help B cells carry out their optimal response? (5)

A
  1. Clonal expansion of specific B cells
  2. Progression to plasma cells
  3. Progression to memory B cells
  4. Isotype switching to IgG, IgA, and IgE
  5. Affinity maturation
32
Q

In what circumstances does a T cell receptor recognise an antigen?

A

When it is a short peptide length and presented in a MHC molecule

33
Q

What happens if a B cell receptor binds strongly to self antigens in the bone marrow?

A

B cell dies by apoptosis

34
Q

What happens if a T cell receptor strongly binds to self antigens in the thymus?

A

T cell dies by apoptosis

35
Q

What cell type does class I MHC present to?

A

CD8 T cells

36
Q

What cell type does class II MHC present to?

A

CD4 T cells

37
Q

Where can MHC I be found?

A

On all nucleated cells

38
Q

Where can MHC II be found?

A

On antigen presenting cells e.g. dendritic cells, macrophages, B cells

39
Q

Which MHC class presents intracellular anitgens?

A

MHC I

40
Q

Which MHC class presents extracellular derived antigens?

A

MHC II

41
Q

Name the type of immunity that the following T cells are responsible for?

a) TH1
b) TH2
c) TH17

A

a) Cellular immunity
b) Antibody immunity
c) Mucosal immunity

42
Q

What are the primary organs of the adaptive immune system?

A

Bone marrow - B cell education

Thymus - T cell education

43
Q

What are the secondary organs of the adaptive immune system?

A

Spleen
Lymph nodes
Mucosal Associated Lymphoid Tissue of GI tract (MALT) and Bronchial Tract (BALT)

44
Q

What is the main function of the spleen?

A

Filters blood of senescent cells and blood borne pathogens