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B4W2 > COORDINATING THE IMMUNE RESPONSE TO INFECTION > Flashcards

COORDINATING THE IMMUNE RESPONSE TO INFECTION Flashcards

1
Q

what are the 4 ways in which we characterise T cells from being different to one another?

A

phenotype, MHC restriction, function and cytokines they produce

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2
Q

what does it mean to say “we can characterise different T cells based on phenotype”?

A

by identifying different molecules expressed on the surface or inside the cell.

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3
Q

what is MHC restriction?

A

T cells will only respond to the antigen when it is bound to a particular MHC molecule

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4
Q

which cells are MHC class 1 and class 2 restricted?

A 
class 1- CD8+
class 2- CD4+
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5
Q

describe what happens in the MHC class 1 antigen presentation pathway?

A

small peptides are delivered into the endoplasmic reticulum. MHC class 1 molecule binds permanently to a small peptide and this is pinched off into a vesicle and migrates to the cell surface where it fuses and presents the antigen to CD8+ T cells.

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6
Q

describe what happens in the MHC class 2 antigen presentation pathway?

A

exogenous antigens are taken up into cells by endocytosis/engulfed. in the endoscope, antigens interact with MHC class 2 molecules, they bind and the vesicle travels to the cell surface and presents the antigen to CD4+ T helper cells.

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7
Q

what is the function of Cd4+Tfh? and what are they?

A

T follicular helper cells

help form the germinal centers and B cell antibody affinity maturation

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8
Q

what is the function of CD4+Th1 cells?

A

activation of phagocytes for enhanced killing of intracellular pathogens

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9
Q

what is the function of CD8+ cells?

A

activation of phagocytes for enhanced killing of intracellular pathogens

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10
Q

What if the function of CD4+ Th2?

A

activation of responses targeting extracellular pathogens

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11
Q

what is the function of CD4+ Th17?

A

activation of neutrophils/autoimmunity/anit-fungal responses

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12
Q

What is the function of CD8+CTL?

A

direct killing of infected target cells or cancer cells

they are cytotoxic T lymphocytes

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13
Q

What is the function of CD4+ Treg?

A

inhibits the functions of other T cells

T regulatory cells

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14
Q

What cytokines do CD4+ produce?

A

IL2

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15
Q

what cytokines do Th1 and CD8+ release?

A

interferon gamma

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16
Q

What cytokines do Th2 release?

A

IL-4

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17
Q

what cytokines do Th17 release?

A

IL-17

18
Q

what cytokines do T follicular helper cells release?

A

IL-21

19
Q

What are the 3 signals T cells need to become activated?

A

T cell receptor engagement
costimulation
cytokines

20
Q

what is T cell receptor engagement?

A

T cell receptors engage with an antigen being presented by an APC

21
Q

what is costimulation in T cell activation?

A

ligands present on the antigen present cells bind to ligand receptors on T cell surfaces. This enhances the first signal.

22
Q

what’s the cytokine phase of T cell activation?

A

phagocytes release cytokines and these tell the T cell what type of cell it should become.

23
Q

What happens after T cell activation?

A

proliferation and differentiation of T cells occurs to produce effector T cells and memory T cells

24
Q

What are the functions of IL-2?

A

to stimulate the proliferation of T cells and allows T lymphocytes to survive under homeostatic conditions

25
Q

Describe clonal expansion of T cells?

A

naive T cells interact with antigens and this initiate proliferation. Activated T cells produce effector T cells and memory cells. memory cells can either remain as memory cells in lymphoid tissue or become effector cells and migrate to tissues. Effector T cells can die or become memory T cells

26
Q

What do effector T cells secrete and have on their surfaces?

A

cytokines

27
Q

Describe the difference between a primary and secondary immune response?

A

after first exposure populations of cells expand slowly and contract again but maintain a higher frequency than before. On second exposure, cells expands faster and to a higher degree and when it declines again the baseline is higher than before

28
Q

why do we have boosters after vaccines?

A

as it increases our base level of memory

29
Q

What happens if a T cell comes into contact with an antigen they recognise in.a lymph node?

A

they start to expand clonally and meet with B cells and help them to produce high affinity antibodies

30
Q

what do follicular helper cells do?

A

they move into the germinal centres in the B cell follicles with a B cell where the B cells can undergo affinity maturation and migrate out as plasma and memory cells.

31
Q

what’s the difference between a type 1 and a type 2 immune response?

A

1- caused by microbes and tissue damage

2- caused by helminths mainly, but also allergies and fibrotic tissue

32
Q

What do T helper 1 and T helper 2 cells produce?

A

Th1- interferon gamma, IL-1, TNF

Th2- IL-4, IL-13, IL-10, Granulocyte-macrophage Colony stimulating factor

33
Q

What are regulatory T cells?

A

Tregs

they control the immune responses to self and foreign antigens and help prevent autoimmune diseases

34
Q

What are senescent T cells?

A

cells that enter a terminal differentiation state due to excessive cell replication

35
Q

What are anergic T cells?

A

an unresponsive state induce by failing to react to an antigen due to only 1/3 signals occuring

36
Q

What is T cell exhaustion?

A

a progressive loss of effector function due o prolonged antigen stimulation

37
Q

why are T cells not effective against cancers?

A

due to T cell exhaustion

38
Q

what are checkpoint inhibitors?

A

Checkpoint Inhibitors Block Antibodies that Hide Cancer Cells from the Immune System

39
Q

what can dendritic cells do?

A

detect pathogens and activate an innate response, eliminate pathogens through phagocytosis, activate T cells which can activate B cells, produce antigen-MHCII complexes so can provide costimulation to active T cells

40
Q

give time scales for the innate and adaptive immune response to kick in

A

innate- 0-4 hours after infection

adaptive- over 96 hours after infection

41
Q

why are antibodies in the secondary response more successful in disposing of antigens?

A

as they have a higher affinity for antigens and there are more of them already

B4W2 (11 decks)

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