Block D Lecture 1: Humoral and Antibody Mediated Immunity

Question 1

What are the 2 times of acquired (specific) immunity?

Answer 1

Cell-mediated Immunity
Antibody-mediated immunity
(Slide 3)

Question 2

What 2 factors decides what response the immune system takes against a pathogen?

Answer 2

Its size
Whether it’s extra or intracellular
(Slide 4)

Question 3

What are the 4 steps of the humoral activation phase?

Answer 3

Phagocytosis of pathogen by Antigen presenting cells (APCs)
Antigen processing / presentation
Education of naïve T cell
Clonal expansion of T cell
(Slide 5)

Question 4

What are the 4 steps of the humoral effector phase?

Answer 4

Uptake of pathogen by B cell
Antigen processing / presentation
Interaction with antigen specific T-cell
Clonal expansion of B cells and differentiation to plasma cell
(Slide 6)

Question 5

What 5 antigens can antibodies recognise?

Answer 5

Proteins
Carbohydrates
Nucleic acids
Glycolipids
Small inorganic molecules
(Slide 7)

Question 6

How many identical light and heavy chains do antibodies have?

Answer 6

2 of each
(Slide 8)

Question 7

What chain of the antibody determines the isotype class of antibody (E.g. IgA, IgD, IgE.. etc)?

Answer 7

The heavy chain
(Slide 8)

Question 8

What makes up the antigen binding regions in an antibody?

Answer 8

The variable regions of both the light and heavy chains
(Slide 8)

Question 9

How many antigen binding regions does an antibody have?

Answer 9

2
(Slide 8)

Question 10

What does the Fc portion (the heavy chain constant regions) bind to?

Answer 10

A cell surface receptor
(Slide 8)

Question 11

What 4 places is IgA antibody found?

Answer 11

Breastmilk
Lung and airways
Intestinal lumen
Urogenital tract
(Slide 11)

Question 12

Where is IgE antibody found?

Answer 12

Connective tissue mast cells
(Slide 11)

Question 13

What 3 places is IgG antibody found?

Answer 13

Blood
Maternal blood (to supply a foetus)
Extravascular tissues
(Slide 11)

Question 14

Where is IgM antibody found?

Answer 14

Blood
(Slide 11)

Question 15

What form of IgA can survive on mucosal surfaces?

Answer 15

The dimeric form
(Slide 12)

Question 16

What is the most common type of primary antibody deficiency?

Answer 16

Selective IgA deficiency
(Slide 12)

Question 17

Why can an IgA deficiency appear asymptomatic?

Answer 17

As IgM can compensate
(Slide 12)

Question 18

What 2 pathogens is IgA important in defending against?

Answer 18

Intestinal pathogens
Virus particles
(Slide 12)

Question 19

What is the main antibody in the secondary response?

Answer 19

IgG
(Slide 14)

Question 20

What does IgG provide to a baby?

Answer 20

Neonatal protection until the baby’s immune system develops
(Slide 14)

Question 21

How does IgG provide neonatal protection to a baby?

Answer 21

By crossing the placenta and into the Fetal bloodstream
(Slide 14)

Question 22

Roughly what percentage of circulating immunoglobulins in the blood are IgG?

Answer 22

75%
(Slide 14)

Question 23

What 4 things does IgG mediate in?

Answer 23

Phagocytosis
Opsonisation
Antibody-dependent cellular cytotoxicity by NK cells
Degranulation of neutrophils, eosinophils and mast cells
(Slide 14)

Question 24

Where is IgD inserted?

Answer 24

Into the B cell membrane
(Slide 16)

Question 25

What does IgD act as after inserted into the B cell membrane?

Answer 25

The B cell receptor for antigens (Slide 16)

Question 26

What is the half-life of IgD?

Answer 26

3 days (Slide 16)

Question 27

What 2 pathogens is IgD thought to be protective against?

Answer 27

Mucosal and respiratory (Slide 16)

Question 28

What antibody is the first antibody secreted in the primary response?

Answer 28

IgM (Slide 17)

Question 29

What is natural IgM?

Answer 29

IgM which is present in babies (Slide 17)

Question 30

What is adaptive IgM?

Answer 30

IgM produced in response to antigenic stimulation of B cells (Slide 17)

Question 31

What 2 types of microbial components can IgM recognise?

Answer 31

Viral antigens and bacterial toxins (Slide 17)

Question 32

What does the high avidity of polymeric IgM mean?

Answer 32

It can immobilise a target at a site (Slide 17)

Question 33

What is IgE meant to protect against?

Answer 33

Worm infestations (Slide 19)

Question 34

What is IgE associated with in 1st world countries?

Answer 34

Type 1 allergic reactions (Slide 19)

Question 35

How is IgE mediated?

Answer 35

Through degranulation of granulocytes (Slide 19)

Question 36

How does IgE release pre-formed mediators?

Answer 36

IgE-mediated activation occurs through FcεRI on mast cells and basophils/multivalent (having multiple sites to attach to an antibody) antigens cross-link the receptor-bound IgE to trigger degranulation and the release of pre-formed mediators (Slide 19)

Question 37

What do the pre-formed mediators release by IgE result in?

Answer 37

Allergic reactions (Slide 19)

Question 38

What does the pro-inflammatory response triggered by IgE induce?

Answer 38

A T helper 2 (Th2) immune response (Slide 19)

Question 39

Where do specific IgE bound to mast cells recognise antigens?

Answer 39

In venom from stings / bites (Slide 19)

Question 40

How can IgE activation inactivate venom from stings / bites?

Answer 40

By causing mast cell degranulation and release of enzymes which inactivate the venom (Slide 19)

Question 41

What are the 6 antibody mediated effector functions?

Answer 41

Neutralisation Agglutination (clump together antibody and pathogen) Opsonisation Activation of complement cascade Antibody-dependent cell mediated cytotoxicity (ADCC) Trigger degranulation of granulocytes (Slide 21)

Question 42

Why are T-independent (T-cell independent) responses fast?

Answer 42

Because B cells are directly activated by antigens with certain types of structure (Slide 23)

Question 43

Why is IgM the only class of antibody that can be produced in T-independent response?

Answer 43

As T cells are needed to help B cells class switch (Slide 23)

Question 44

What is the disadvantage of T-independent response?

Answer 44

Short life-span and are therefore not protective (Slide 23)

Question 45

Does T-independent response make memory cells?

Answer 45

No (Slide 23)

Question 46

What are T-dependent (TD) antigens?

Answer 46

Antigens that require the involvement of T cells to start a strong immune response (Slide 24)

Question 47

What 6 functions requires T lymphocyte (T cells) to B lymphocytes (B cells)?

Answer 47

B cell proliferation Production of immunoglobulins Immunoglobulin class switching Rescue of B cells from apoptotic death Germinal centre formation Generation of B lymphocyte memory (Memory B cells) (Slide 24)

Question 48

What 2 classes can T-independent (TI) antigens be divided into?

Answer 48

TI-1 (TI type 1) TI-2 (TI type 2) (Slide 25)

Question 49

What are TI type 1 (TI-1) antigens?

Answer 49

Polyclonal (derived from many clones) B cell activators (Slide 25)

Question 50

What are TI type 2 (TI-2) antigens?

Answer 50

Antigens able to directly stimulate B cells (Slide 25)

Question 51

What antibody is specialised to activate complement efficiently upon binding an antigen?

Answer 51

IgM (Slide 28)

Question 52

What are the primary and secondary immune responses?

Answer 52

The primary immune response is the first time the immune system encounters an antigen and the secondary immune response is any subsequent times it encounters the antigen (Slide 30)

Question 52

How do memory cells make the secondary immune response faster?

Answer 52

As they remember each antigen encountered (Slide 30)