Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICR2209 > 6 - Adaptive immunity (humoral immune responses) > Flashcards

6 - Adaptive immunity (humoral immune responses) Flashcards

1
Q

What is a humoral immune response mediated by

A

Antibodies secreted by plasma cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Outcomes of humoral immune response

A
  • Antibody secretion
  • Isotype switching
  • Affinity maturation
  • Memory B cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

BCR

A

B cell receptor. Membrane bound immunoglobulin (IgM/IgD) with a unique specificity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do activated B cells act as

A

Professional APC (present antigen and costimulatory molecules to T cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Two roles of BCR in B cell activation

A
  • Performs first signal of activation (binding to
    cognate antigen)
  • Internalise antigen (APC function) so it can be
    processed, and peptides presented on MHC
    class II molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Antibody (immunoglobulin) structure

A

Four polypeptide chains: two identical heavy (H) chains and two identical light (L) chains, with each chain containing a variable region and a constant region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Hypervariable regions

A

Each variable region of the heavy chain (VH) or of the
light chain (VL) contains three hypervariable regions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 5 classes of antibodies

A

IgM, IgD,IgG, IgA and IgE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Fab region

A

Fragment, antigen binding region, variable region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What bonds hold together antibodies

A

Disulfide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Fc region

A

Fragment, crystalline (tail, constant region, effector)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Gene rearrangment and BCR diversity

A
  • A random variable region gene segments is selected and joined to a downstream DNA segment
  • Process in bone marrow and is independent of presence of antigens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where do B cells mature

A

Secondary lymphoid tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to immature B lymphocytes that recognise self antigens

A

either change their specificity (receptor editing) or are deleted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Two types of B cell activation

A

T independent and T dependent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

T independent B cell activation

A
  • Antigens are multivalent (e.g., bacterial polysaccharides)
  • Responses are fast (1-2 days)
  • Predominantly IgM
  • Low affinity
  • Short-lived plasma cells
  • Weak in infants and young children
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

T dependent B cell activation

A
  • Antigens must contain a protein component
  • B cell receives two signals
  • Responses are slower (several days),
  • All immunoglobulin isotypes are
    produced
  • High-affinity
  • Memory B cells and long-lived plasma cells
15
Q

Two signals that B cell receives during T dependent B cell activation

A
  1. Through its antigen receptor
  2. Through interaction with T helper cell that recognises degraded fragments of the
    same antigens
16
Q

Linked recognition

A
  • B and T cells see the same parts of the same antigen
  • Requires precise regulation of the migration of activated B and T cells into specific locations
17
Q

Migration of B and T cells

A
  • Activated CD4 T cells and activated B cells migrate toward one another and interact at the edges of the follicles, where the initial antibody response develops
  • Some of the cells migrate back into follicles to form germinal center, where the more specialised antibody responses are induced
18
Q

B cell activation pathway

A

Activation of B cells and migration to germinal center –> B cell proliferation –> Somatic mutation and affinity maturation (isotype switching) –> Exit of high affinity antibody secreting cells and memory B cells

19
Q

What is essential for B cell activation

A
  • Interaction between CD40 on the B cells and CD40 ligand on the T cells
  • Cytokines (e.g., IL-4, IL-21)
20
Q

How is an effective vaccine against H.influenzae type b for children made

A
  • The H. influenzae polysaccharide is linked chemically to tetanus toxoid, a protein against which infants are vaccinated (conjugate polysaccharide vaccines)
  • B cells that bind the
    polysaccharide component
    of the vaccine are activated by helper T cells specific for tetanus toxoid antigen, generated previously
21
Q

Affinity maturation

A

Process by which the affinity of antibodies produced in response to a protein antigen increases with prolonged or repeated exposure to that antigen

22
Q

What causes affinity maturation

A

Caused by point mutations in the V regions of the genes
encoding the antibodies produced, particularly in the
antigen-binding hypervariable regions

23
Q

Heavy chain isotype (class) switching

A

Helper T cells stimulate the progeny of B lymphocytes to change the heavy-chain isotypes (classes) of the antibodies they produce, without changing their antigen specificities

24
Q

X-linked hyper-IgM syndrome

A

caused by mutations in the CD40L gene –> much of the serum antibody is IgM, because of defective heavy-chain isotype switching

25
Q

Which antibodies predominate in blood

A

IgG and IgM

26
Q

what are the major antibodies in extracellular fluid within the body

A

IgG and IgA

27
Q

Which antibodies predominate in secretions across epithelia, including breast milk

A

IgA

28
Q

Which antibodies for the foetus receive from mother by transplacental transport

A

IgG

29
Q

Where is IgE found

A

mainly associated with mast cells just beneath epithelial
surfaces particularly in respiratory tract, gastrointestinal tract and skin

30
Q

IgA function

A

Protect epithelial surfaces from infectious agents. Neutralises pathogens and their toxins

31
Q

IgM function

A

Complement activation

32
Q

IgE function

A

Binds to mast cell FcεRI triggering rapid degranulation, releasing inflammatory mediators into
surrounding tissue

33
Q

IgG function

A
  • Fc receptor dependent phagocyte responses
  • Complement activation
  • Neonatal immunity
34
Q

Fc gamma receptors

A

Facilitate phagocytosis of antibody bound cells

35
Q

Antibody Dependent Cellular Cytotoxicity (ADCC)

A

FcγRIII in NK cells binds to IgG antibodies attached to the surface of a cell, leading NK cell to discharge its granule proteins into the cell, killing it

36
Q

Secondary vs primary response

A

Secondary response is much
more rapid, and the total antibody production is nearly 1,000 times
greater than that of the primary response

37
Q

Antibody titer

A

measurement of serum antibody, and can be used to study antibody dynamics

38
Q
A

MICR2209 (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions