Adaptive Immune System- Focus On B Cells Flashcards

1
Q

What is an antigen?

A

Any substance that can induce an adaptive immune response

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2
Q

Name a few things that antigens can be made up of

A

Short peptides, proteins, sugars, lipids and more

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3
Q

What is an antibody?

A

Proteins produced by adaptive immune cells that bind specifically to antigenic determinants

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4
Q

What is an antigenic determinant?

A

Relatively small part of foreign molecules that antibodies bind to

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5
Q

What is a cytokine?

A

General term to describe various small proteins secreted by cells that serve to regulate the immune system

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6
Q

How are cytokines named?

A

Often interleukin followed by a number but sometimes have other names linked to their function

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7
Q

What are chemokines?

A

The subtype of immune molecules that are involved in the movement and migration of immune cells

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8
Q

How do chemokines move cells?

A

Release chemicals in a gradient which guide the cells

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9
Q

What does CD stand for?

A

Cluster of differentiation

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10
Q

What is a CD?

A

Defines cell-surface molecules on immune cells that are recognised by specific monoclonal antibodies

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11
Q

What does the number after the CD stand for?

A

The order of its discovery

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12
Q

Do CDs have to be expressed specifically to one cell lineage?

A

No, can be found on many lineages

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13
Q

What is the defining characteristic of adaptive immunity?

A

Immune response is directed at a specific pathogens antigen and memory persists after initial encounter

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14
Q

What do lymphoid precursors do if they move into the thymus?

A

Mature into T cells

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15
Q

What do lymphoid cells mature into in the bone marrow?

A

B cells

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16
Q

What are the three large groups of B cell?

A

B1, B2 and regulatory B cells

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17
Q

Where do B1 cells mature?

A

In the liver

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18
Q

Where do B1 cells end up?

A

Peritoneum

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19
Q

Which immunoglobulin do B1 cells express on the cell surface?

A

IgM

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20
Q

What is the function of B1 cells?

A

Produce natural antibodies That are present in the absence of infection.

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21
Q

Do B1 cells require T cell help?

A

No

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22
Q

Where do B2 cells mature?

A

Bone marrow and spleen

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23
Q

What are the three types of B2 cell?

A

Follicular, transitional or marginal

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24
Q

Which is the most common type of B2 cell?

A

Follicular

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25
Q

Where are the follicular B2 cells located?

A

Secondary lymphoid organs (spleen, tonsils, lymph nodes)

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26
Q

Which type of B2 cell makes the majority of high affinity antibodies?

A

Follicular B2 cells

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27
Q

Do follicular B2 cells require T cell help?

A

Yes

28
Q

Where are marginal zone B2 cells found?

A

In the spleen

29
Q

What are the marginal zone B2 cells function?

A

First line of defence against blood-bourne pathogens

30
Q

Do marginal zone B2 cells require T cell help?

A

May or may not

31
Q

What is the function of regulatory B cells?

A

Produce responses that regulate the other two types

32
Q

What are the three stages of primary adaptive response?

A

Activation, proliferation and memory cells

33
Q

Why does the immune response decrease over time?

A

To maintain homeostasis

34
Q

What is the significance of the antibodies being specific?

A

Makes sure the response to a microbe is directed at a particular antigen of that microbe

35
Q

What is the significance of the antibodies being diverse?

A

The immune system is able to respond to a large variety of antigens

36
Q

What is the significance of the antibodies doing clonal selection and expansion?

A

Increases the number of antigen-specific lymphocytes to keep pace with microbes

37
Q

What is the significance of the antibodies being specialised?

A

Generates optimal responses against different types of microbes

38
Q

What is the significance of the antibodies contraction and homeostasis?

A

Allows for recovery and to avoid collateral damage

39
Q

What is the significance of the antibodies having a memory?

A

Increases the ability of the cell to combat repeated infections

40
Q

What is the significance of the antibodies having a very low reactivity to self?

A

Prevents injury to the host

41
Q

What are a lot of the symptoms of infection due to?

A

Collateral damage of the immune system and not directly related to the bug itself

42
Q

What are Ig glycoproteins made up of?

A

tetrameric - 2 light chains and two heavy chains

43
Q

How are the two light and two heavy chains held together?

A

Non-covalent interactions and disulfide cross links between cysteine residues

44
Q

How are Ig glycoproteins shaped?

A

Y shaped

45
Q

What is the fab fraction of the antibody?

A

Antigen binding bit

46
Q

What can the Fc fraction of the antibody be used to create?

A

crystals

47
Q

How are antibodies split into their Fab and Fc fractions?

A

Proteases cut the molecule at the hinge region

48
Q

What is the function of the variable region?

A

To bind to the antigen

49
Q

What is the constant region of an antibody responsible for?

A

Effector functions (activating complement, binding to phagocytes etc)

50
Q

What is the idiotype?

A

The variable region tip

51
Q

What is the isotype?

A

The Fc fraction and the bottom half of the variable region

52
Q

What is the tip of the Ig variable region called?

A

CDRs- complement determining regions

53
Q

How does an antibody bind to an antigen?

A

Electrostatic, hydrophobic, van der waals forces and hydrogen bonds

54
Q

What is a linear determinant?

A

The Ig can bind to the determinant in both the native and denatured protein

55
Q

What is a conformational determinant?

A

The Ig can only bind if the protein is folded

56
Q

What are the two ways an antibody can be found?

A

The surface of a B cell or secreted from a B cell

57
Q

How is an antibody attached to the surface of a B cell?

A

Anchored to the surface, with a TMD and a cytoplasmic tail

58
Q

How does the body make millions of different B cells with different random antigen binding sites?

A

Ig gene rearrangement, receptor editing, selection or somatic hypermutation

59
Q

How does clonal selection and expansion work?

A

Lymphocyte clones mature into generative lymphoid organs
Clones of mature lymphocytes specific for diverse antigens enter the lymphoid tissues
Antigen-specific clones are activated by antigens
Antigen-specific immune responses occur

60
Q

Why are most antibody responses polyclonal?

A

More than one clone of B cells is generated or more than one Ig is synthesised

61
Q

What are the 5 types of immunoglobulin isotopes?

A
IgG (gamma) 
IgA (alpha)
IgM (mu)
IgE (epsilon)
IgD (delta)
62
Q

Which Ig isotype has the most subclasses (and what are their names)?

A

IgG

1, 2, 3, 4

63
Q

What is the Ig isotope that forms a pentameter?

A

IgM

64
Q

Which Ig isotope dimerises?

A

IgA

65
Q

What can the IgA dimer do that IgA on its own cannot?

A

Cross the muscosal barriers in the gut

66
Q

What are the 6 antibody effector functions?

A
  • neutralisation
  • opsonisation and phagocytosis of microbes
  • antibody dependant cellular cytotoxicity
  • phagocytosis of microbes with complement fragments
  • inflammation
  • lysis of microbes
67
Q

What are the two ways antibodies can opsonise a pathogen?

A
Neutralise it (bind to the toxin so they cant attack cells)
Or bind to the antigens on the bacterial cell surface, which makes phagocytosis more efficient