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Infection > Adaptive Immunity > Flashcards

Adaptive Immunity Flashcards

1
Q

Where are T cells made and matured?

A

Made in bone marrow matured in thymus

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2
Q

What allows for antigen-T cell recognition?

A

T cell receptor - these are diverse

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3
Q

What is a naive T cell

A

Not activated yet by APC

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4
Q

3 features of APCs?

A

Strategic location - lymphoid tissue, skin, MALT, lymph nodes
Pathogen Capture - phagocytosis/macropinocytosis
Diversity in pathogen sensors (PRRs) - bacteria/virus

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5
Q

What is the location of B cells

A

Lymphoid tissues

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6
Q

Name 4 types of APC

A

Macrophages
Dendritic Cells
B cells
Langerhans cells (dendritic cells of skin)

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7
Q

What 3 places can you find dendritic cells

A

Lymphoid tissue
Blood
Mucus membranes

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8
Q

Where would you find langerhans cells?

A

Skin

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9
Q

Where would you find macrophages?

A

Everywhere

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10
Q

Where would you find B cells?

A

Lymphoid tissues

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11
Q

Which APCs present to naive T cells

A

Dendritic cells
Langerhans cells
B cells

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12
Q

Which APCs present to effector T cells

A

Macrophages

B cells

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13
Q

What is the 3 roles of APC?

A

Capture
Process
Presentation

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14
Q

What cells must be presented with antigens to perform immune response?

A

T cells (naive)

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15
Q

What determines the immune response?

A

APC via the MHC molecule it displays

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16
Q

4 characteristics about MHC molecules that make them respond to a diverse range of microbes?

A

1) Parent alleles are co-expressed = recognise more pathogens
2) Polymorphic - gives population immunity as prevents infection spreading as people immune to different things
3) Peptide (antigen) binding cleft is polymorphic meaning can bind different antigens
4) Specificity is broad - MHC molecules can present >1 peptide, can present different parts of microbe with same MHC molecule or can present different microbes

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17
Q

What is humoral vs cell-mediated immunity?

A

Humoral - MHCII - bacteria - CD4+ B cells - antibodies

Cell-mediated - MHCI - viral - CD8+ - cytotoxic T cells

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18
Q

What are the HLAs for MHC I an II

A

MHCI A B C

MHCII DP DQ DR

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19
Q

Professional APCs primarily present MHCII and all nucleated body cells present MHCI true or false?

A

True

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20
Q

Would a patient show a virus show HLA DP DQ DR?

A

No as this is MHCII

Would show MHCI

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21
Q

What does susceptibility to infection depend on?

A

Type of MHC molecule

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22
Q

What characteristic of MHC molecule promotes human survival?

A

Polymorphism

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23
Q

Which MHC classes can intracellular and extracellular microbes present and why?

A

Intracellular both MHC I and II - Because CD4+ needed for CD8+

Extracellular MHC II just CD4+

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24
Q

What is the role of CD4+ in viruses?

A

Activates CD8+

25
Q

What does the T Cell receptor recognise?

A

MHC-antigen complex on APC

26
Q

What happens once APCs present antigens?

A

They mature

Give off costimulatory signals (cytokines) that help enhance the interaction between TCR and MHC-antigen complex

27
Q

What 3 receptor interactions do T helper cells need in order to be activated?

A

MHC-CD4 interaction
CD80/86 (microbe)-CD28 (T cell) bound
Antigen - TCR interaction

28
Q

What type of T helper cells are for extracellular microbes (2) which are for intracellular (1) ?

A

Extra - TH2, TH17

Intra- TH1

29
Q

How come some MHCI molecules recognise bacteria?

A

As some bacteria act intracellularly

30
Q

What are interferons?

A

Cytokines released by virally infected cells that increases neighbouring cells anti-viral defenses

‘Remember interferons - interfere with viruses to prevent replication etc’

31
Q

What 3 methods of killing are there for intracellular microbes?

A
  • Cytotoxic T lymphocytes
  • Macrophages
  • Antibodies
32
Q

What 4 responses against extracellular microbes are there?

A
  • Bcell Antibodies
  • Eosinophils
  • Neutrophils
  • Mast cells
33
Q

What is the linkage between antibodies and macrophages (2)?

A

Antibodies neutralise the pathogen (antigen) and then macrophages phagocytose it.

Antibodies are also opsonins for phagocytes

34
Q

Which 3 extracellular responses are mediated by TH2?

A

Mast cells
Eosinophils
Antibodies

35
Q

Which extracellular response is mediated by TH17?

A

Neutrophils

36
Q

What interleukins are responsible for mediating extracellular responses to pathogens?

A

IL-5 - Eosinophils
IL-4 - Mast cells and B cells
IL-17 - Neutrophils

37
Q

Which interferons are responsible for mediating intracellular responses to pathogens?

A

IFg for CD4+ (B cells and macrophages)

38
Q

Which antibody is a really good opsonin

A

IgG

39
Q

What are the 4 antibodies from the lecture?

A

IgG
IgM
IgA
IgE

40
Q

What are the immune functions of the different antibodies? Which one do you get given during pregnancy?

A

IgG - Fc-dependent phagocytosis, complement activation, neonatal immunity, toxin/virus neutralisation
IgM - complement activation, appear early in course of infection, appear again to a lesser extent in subsequent exposure
IgA - mucosal immunity, tears, saliva, GI, GU, resp
IgE - Helminth/parasite immunity, mast cell degranulation in allergies, release histamine etc

IgG get given

41
Q

Why is there are 2-3 day lag phase for antibody production?

A

Because B cells have to differentiate into plasma cells and produce antibodies

42
Q

What 4 medical achievements are there that have derived from the study of the adaptive immune system?

A

1) Vaccination
2) Immunoglobulin therapies
3) Passive immunity (antibody transfer)
4) Antibody based diagnostic tests e.g. blood tests/infectious/autoimmune

43
Q

What are perforins granzymes?

A

Used by cytotoxic T cells to induce apoptosis in infected cells

44
Q

Which cells present MHCI

A

All nucleated cells so not RBC

45
Q

Which cells present MHCII

A

Professional APCs

46
Q

Do CD4+ or CD8+ cells present antigens?

A

NO

47
Q

do B cells present antigens

A

Yes

48
Q

How do APCs activate naive T cells –> helper T cells (3 receptor interactions + something else)

What is the term used to describe these signals?

A

1) MHCII -> CD4 protein
2) Antigen –> TCR
3) CD80/86 (co-stimulators) –> CD28
4) Cytokines from APC to T cell

‘costimulatory signals’

49
Q

Roughy how do B cells get activated by T cells?

A

Binding MHC-antigen to TCR and release of cytokines from T cells that act on B cells and activate them –> differentiate into plasma cells and can then produce antigens

50
Q

Which type of T cells cause damage during organ transplant rejection and autoimmune disease?

A

CD8+ cytotoxic T cells

51
Q

What might someone be called if they have HIV but a CD4+ count over 500cell/ul without antiretroviral therapy? What does it mean?

A

Elite controllers
Long term nonprogressors

Means they can control viral replication

52
Q

What are perforins and granzymes and what 2 other things are they similar to?

A

Granzymes - proteases induce cell apoptosis in cells infected with virus/bacteria/cancer

Perforins - cytolytic create pores in cell membrane to kill cells

Similar to cytolysins in gram pos bacteria
Similar to C9 membrane attack of complement system

53
Q

What is the basis of a slow progressor in HIV?

A

MHCI molecules present important peptides that are essential for the virus survival
Hence effective T cell response to virus so it doesn’t progress very quickly

Rapid progressors’ MHC I molecules present unimportant peptides to viral survival hence less effective T cell response and rapidly progressing disease

54
Q

What two ways can MHC molecules present a problem with organ transplant rejection? What is graft vs host reaction?

A
  • Different HLA molecules between donor and recipient
  • MHC also presents self peptides - WBCs in organ transplant may be recognise self as foreign
    Graft vs Host reaction - graft
55
Q

Which HLA molecule is associated with rapid or slow progress ors of HIV?

A

HLA B

56
Q

Which HLA molecules are associated with ankylosing spondylitis and Insulin dependant diabetes mellitus?

A

HLA B

HLA DQ

57
Q

What happens to the immune response the 2nd exposure (5)

A 
Faster
Longer
Stronger
Higher affinity
Isotope switch IgM --> IgG
58
Q

What is the Fc region of antibodies?

A

Region that binds to Fc receptors on immune cells e.g. B cells dendritic cells macrophages

It mediates the physiological effects of antibodies

59
Q

What are the physiological effects of antibodies

A

Opsonise for phagocytosis
Neutralise pathogen
Cell lysis
Degranulation of mast cells eosinophils basophils

Infection (14 decks)

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