Cells of the Immune System

Question 1

What are the two soluble factors of innate immunity?

Answer 1

Antibacterial factors

Complement system

Question 2

What is a cellular factor of innate immunity?

Answer 2

Scavenger phagocytes

Question 3

What are two types of antibacterial factors?

Answer 3

Lysozymes

Lactoferrin

Question 4

How to lysozymes work as part of innate immunity?

Answer 4

Present at mucosal surfaces

Active in breaking down the gram positive cell wall of bacteria

Question 5

How does lactoferrin work as part of innate immunity?

Answer 5

Present at mucosal surfaces

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

Question 6

What are the three final pathways of the complement system?

Answer 6

Opsonisation of pathogens
Recruitment of inflammatory cells
Killing of pathogens

Question 7

What are the two functions of macrophages in immunity?

Answer 7

Clearance of microorganisms

Recruitment of help from other cells e.g. lymphocytes

Question 8

What are macrophages (tissue) derived from?

Answer 8

Monocytes (blood)

Question 9

What are the three main roles of macrophages?

Answer 9

Phagocytosis

Antigen presentation - presents to T cells in MHC II

Cytokine production

Question 10

What is the role of pattern recognition receptors?

Answer 10

Recognises extracellular and intracellular threats to produce a response

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

Question 11

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

Answer 11

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

Question 12

What percentage of white blood cells is composed of neutrophils?

Answer 12

50-70%

Question 13

What are the main roles of neutrophils? (4)

Answer 13

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

Question 14

What percentage of white blood cells is composed of eosinophils?

Answer 14

1-6%

Question 15

What to eosinophils usually respond to in immunity?

Answer 15

Parasites

Question 16

What pathological mechanism can be caused by eosinophils?

Answer 16

Allergy

Question 17

What are the main roles of eosinophils? (3)

Answer 17

Chemotaxis - in response to chemokines

Degranulation - releases toxins onto surface of parasites

Cytokine production - drives inflammation

Question 18

What sites to mast cells guard?

Answer 18

Mucosal sites

Question 19

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

Answer 19

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

Question 20

Where are dendritic cells derived from?

Answer 20

Monocytes - same as macrophages

Question 21

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

Answer 21

ANTIGEN PRESENTATION - can initiate the adaptive immune response

Phagocytosis

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

Question 22

What is the role of the Fc region on antibodies?

Answer 22

Binds to Fc receptors on phagocytes

Activates complement

Question 23

What are the three main roles of antibodies?

Answer 23

Opsonise for phagocytosis

Activate complement system

Neutralise toxins and pathogen binding sites

Question 24

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

Answer 24

IgM

Question 25

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

Answer 25

IgG

Question 26

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

Answer 26

IgM lower affinity than IgG

Question 27

Which antibody can cross the placenta?

Answer 27

IgG

Question 28

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

Answer 28

IgA Neutralises by blocking the binding of pathogens

Question 29

What is the role of IgE in immunity?

Answer 29

High affinity Binds to mast cells through the Fce receptor Also has a role in allergy

Question 30

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

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

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

Answer 33

B cell dies by apoptosis

Question 34

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

Answer 34

T cell dies by apoptosis

Question 35

What cell type does class I MHC present to?

Answer 35

CD8 T cells

Question 36

What cell type does class II MHC present to?

Answer 36

CD4 T cells

Question 37

Where can MHC I be found?

Answer 37

On all nucleated cells

Question 38

Where can MHC II be found?

Answer 38

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

Question 39

Which MHC class presents intracellular anitgens?

Answer 39

MHC I

Question 40

Which MHC class presents extracellular derived antigens?

Answer 40

MHC II

Question 41

Name the type of immunity that the following T cells are responsible for? a) TH1 b) TH2 c) TH17

Answer 41

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

Question 42

What are the primary organs of the adaptive immune system?

Answer 42

Bone marrow - B cell education | Thymus - T cell education

Question 43

What are the secondary organs of the adaptive immune system?

Answer 43

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

Question 44

What is the main function of the spleen?

Answer 44

Filters blood of senescent cells and blood borne pathogens