Lecture 12 - Adaptive Immune Response (Effector Phase) Flashcards

1
Q

Which molecules on APCs present Extracellular microbes antigens to naive T cells?

A

MHC Class II

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2
Q

Which Naive T cells have extracellular antigens presented to them by MHC Class II molecules?

A

CD4+ T cells

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3
Q

What type of Immunity do activated CD4+ cells produce?

A

Humoral immunity (antibodies)

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4
Q

Which molecules on APCs present Intracellular microbes antigens to naive T cells?

A

MHC Class I molecules

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5
Q

Which Naive T cells have intracellular antigens presented to them by MHC Class I molecules?

A

CD8+ T cells

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6
Q

What type of Immunity do activated CD8+ cells produce?

A

Cell-mediated immunity (Cytotoxic T cell response)

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7
Q

Once an APC has captured a microbe where does it migrate to and what part of this area does it go to?

A

Lymphatics/lymph node

Parafollicular cortex

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8
Q

Why does an APC that’s captured a microbe migrate to the parafollicular cortex?

A

Has many T cells here so activate the maximum amount of T cells

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9
Q

Where are T and B cells produced?

A

Bone marrow

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10
Q

Where do T cells mature?

A

Thymus

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11
Q

Where do B cells mature?

A

When they come into contact with antigens in the blood

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12
Q

What is lymphadenopathy?

A

When the lymph nodes swell

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13
Q

Why can lymphadenopathy happen with infection?

A

Swell in infection due to T cells and B cells proliferating

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14
Q

What organ is absent/poorly developed in Digeorge syndrome?

A

Thymus or Spleen

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15
Q

Why is a patient with Digeorge syndrome immunocompromised?

A

No poorly developed thymus

This is where T cells mature

So very few or no mature T cells

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16
Q

What are antigen receptors on T lymphocytes called?

A

T Cell Receptors (TCR)

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17
Q

Where are the 2 extracellular regions of a T cell receptor?

A

Variable region
Constant region

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18
Q

Which region of a T cell receptor does the pathogens peptide/antigen bind to?

A

Variable region

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19
Q

What enables the variable regions of T cell receptors to be able to recognise many antigens?

A

Different segments of genes are randomly expressed generating many combinations that can recognise many different antigens

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20
Q

If T cell receptors can recognise all antigens/peptides, what limits our T cells activating against all pathogens?

A

T lymphocytes only get activated by peptides that are presented by Antigen Presenting Cells (APCs)

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21
Q

What MHC molecule must present a peptide for Helper T cells (CD4+) to recognise it?

A

MHC Class II

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22
Q

What MHC molecule must present a peptide for Cytotoxic T cells (CD8+) to recognise it?

A

MHC Class I

23
Q

What are the 3 signals on an APC that is needed to activate a T cell?

A

Signal 1 = MHC molecule with peptide
Signal 2 = B7
Signal 3 = Cytokines

24
Q

What structure does the peptide attached to the MHC molecule on the APC bind to on the T cell?

A

T cell Receptor at the variable region

25
Q

What structure does the B7 strucutre on the APC attach to on the T cell?

A

CD28

26
Q

What are some inflammatory cytokines?

A

IL-6
IL-1
TNF-a

27
Q

If a pathogen that has been presented by an APC to a naive CD4+ cell is intracellular, what cytokine is the APC going to produce?

What type of immunity is wanting to be achieved?

A

IL-12

Cell mediated immunity

28
Q

What helper T cell (Th) is a naive CD4+ going to differentiate into once exposed to IL-12?

A

Th1

29
Q

What is the function of the T helper 1 cell (Th1)?

A

Stimulates CD8+ T cells to become cytotoxic T cells

Activates macrophages

30
Q

If a pathogen that has been presented by an APC to a naive CD4+ cell is extracellular (like a parasite), what cytokine is the APC going to produce?

What type of immunity is wanting to be achieved?

A

IL-4

Humoral immunity

31
Q

What T Helper cell is formed by a naive CD4+ T cell when IL-4 is produced?

A

Th2

32
Q

What is the function of the T Helper 2 cell (Th2)?

A

Activates B cells producing IgE and IgG
The IgE attracts eosinophils which are good at killing pathogens (parasites)

Mast cells drive allergies

33
Q

What T helper cell is important in recruiting and activating Neutrophils?

A

Th17

34
Q

What interleukins are produced by Antigen Presenting cells which stimulate naive CD4+ T cells to differentiate into Th17 cells (T helper 17)??

A

IL-1
IL-6

35
Q

What is the function of Effector CD8+ T cells?

A

Cytotoxic T cells destroying infected cells

36
Q

Why do levels of Cytotoxic T cells (Effector CD8+ cells) fall as levels of CD4+ T cells fall?

A

Th1 cells are differentiated types of CD4+ cells
Th1 cells produce certain cytokines which trigger CD8+ cells to become Cytotoxic T cells (Effector CD8+ T cells)

37
Q

How do cytotoxic T cells (effector CD8+ T cells) work?

A

MHC molecule on infected cell displays pathogens peptide
Cytotoxic cell binds
Produces enzymes like performing putting holes in the cells membrane
Then injects granzymes inducing APOPTOSIS

38
Q

What type of molecule is the antigen recognition receptor on a B lymphocyte?

A

BCR = Membrane Bound Antibody

39
Q

What are the 2 main regions of an antibody?

A

Variable region (where antigen binds)
Constant region

40
Q

How does a B cell get activated?

A

Antigen binds and forms cross link between 2 receptors/antibodies

41
Q

How do B cells act as APCs to T helper cells?

A

Display pathogens antigen on MHC molecule to T cell receptor on T helper cell
Displays B7 which binds to T helper cells CD28
CD40 Displayed on B cell surface and CD40L from T helper binds to it

42
Q

What is the function of activating CD40 on the B cell?

A

Stimulates the B cell to change from producing IgM to IgG

43
Q

What is the condition called when a patients B cells have a defect in CD40?

A

Hyper IgM syndrome

44
Q

What is the T helper independent antibody produced by a B cell?

A

IgM

45
Q

What are the T helper DEPENDANT antibodies produced by activated B cells?

A

IgG
IgA
IgE

46
Q

When B lymphocytes are activated, what cells do they form which last for a very long time?

A

Memory B cells

47
Q

What is the antibody that responds to Thymus independent antigens which buys time for the body?

A

IgM

48
Q

Why is the antibody IgM described as being a response to thymus independent antigens?

A

Involves no T cells

49
Q

Where are IgA antibodies found?

A

Mucosal surfaces

50
Q

What does IgM do?

A

Compliment activation

51
Q

What does IgE do?

A

Immunity against helminths = parasitic worms
Mast cell degranulation (allergies)

52
Q

What antibody from the mother provides neonatal immunity, activates complement and neutralises toxins?

A

IgG

53
Q

If there is more IgM than IgG has a patient encountered this pathogen before?

A

No this is the bodies first response to it

54
Q

What serological test can be done to see if someone has encountered a disease before/

A

Check if they have the IgG antibody for that disease