L09 Flashcards

1
Q

Different effector mechanisms depend on

A

Type of pathogen, localisation and stage of infection

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2
Q

What type of MHC class would be required for an extracellular infection?

A

MHC II

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3
Q

What type of MHC class would be required for an intracellular infection?

A

MHC I

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4
Q

What are the innate defenses against viruses

A

Interferons and NK cells

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5
Q

What type of interferons are present in responding to a virus

A

IFN - alpha and beta

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6
Q

How do IFN-alpha and IFN-beta help respond to the virus?

A

Prevents nucleic acid production/replication

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7
Q

What do chemokines recruit?

A

Lymphocytes

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7
Q

How does IFN-alpha and IFN-beta prevent viral nucleic acid production/replication

A

Induce resistance to viral replication in all cells by inducing Mx proteins, 2’-5’ linked adenosine oligomers, and the kinase PKR.

Increase MHC class I expression and AG presentation in all cells

Activate dendritic cells and MQ

Activate NK cells to kill virus-infected cells

Induce chemokines to recruit lymphocytes

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8
Q

What type of interferons are there?

A

1

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9
Q

How does IFN result in viral mRNA degradation?

A

2,5’ - oligoadenylate synthetase = adenine trinucleotide synthesis = activates endonuclease = degrades viral mRNA

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10
Q

How does IFN inhibit protein synthesis

A

Protein kinase = phosphorlyation and inactivation of eIF-2 = inhibits protein synthesis

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11
Q

What cells make IFN alpha and beta?

A

Infected cell

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12
Q

When is IFN alpha and beta synthesised?

A

Early response to infection

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13
Q

What cells secrete type II IFN (IFN - gamma)

A

NK and activated T cells

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14
Q

What does IFN gamma do?

A

Inhibits TH2 response (Ab), promotes TH1 (NK), recruits Mq

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15
Q

What are the therapeutic use of interferons?

A

rIFN-alpha - hepatitis B and C, some cancers.

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16
Q

What are the disadvantages of using IFN for therapeutic treatments?

A

Side effects can be severe

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17
Q

Why can there be severe side effects for therapeutic treatments using IFN?

A

Cytokine storm -> excessive immune response can damage healthy cells and organs

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18
Q

Are NK cells large granular lymphocytes?

A

Yes

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19
Q

What are the components of the extracellular mechanism used by NK cells to kill infected cells?

A

Perforins and granzyme

19
Q

How do NK cells recognise stressed cells in the absence of Ig and MHC?

A

Recognise structures on viral infected cells

20
Q

What are the 2 types of NK cell receptors?

A

Activating receptors and inhibitory receptors

21
Q

What do activating receptors do?

A

recognise carbohydrate ligands = trigger killing of the cell

22
Q

What do inhibitory receptors do?

A

recognise MHC class I

23
Q

What are the only type of receptors on T cells that can perform binding?

A

TCR

24
Q

If a virus can reduce MHC expression - what would this result in?

A

Result in killing of the infected cell

25
Q

How would reduced MHC result in apoptosis of the infected cell?

A

There would be no interaction between MHC and inhibitory receptor resulting in the activation of NK = apoptosis

26
Q

What are the components of cell mediated specific immunity?IF

A

Cytotoxic T cells (CD8) and cytokines with anti-viral activity

27
Q

Give an example of a cytokine involved in anti-viral activity and what it does?

A

IFN gamma - activates Mq

28
Q

What are the two mechanisms through which cytotoxic T cells induce apoptosis

A
  1. secretion of cytotoxic granules
    perforin & granzymes
  2. Fas ligand on T cell interacts with Fas on target = apoptosis
29
Q

How does perforin make pores in the membrane?

A

Through polymerisation

30
Q

What cytokines are secreted by CD8?I

A

IFN gamma

31
Q

What does IFN gamma result in?

A

Inhibits viral replication
Upregulates MHC class I and II expression and antigen presentation
Increases macrophage phagocytosis of dead cells
Promotes NK cell killing activity

32
Q

What is the role of Ab in viral infection responses

A

Antibodies
Neutralise free virus (prevent entry into and spread between cells)
Can prevent spread within the body (e.g. poliovirus) or protect mucosal surfaces against reinfection (e.g. ‘flu’)
Opsonise to increase phagocytosis
Activate complement leading to lysis (enveloped viruses)

33
Q

What is the role of Ab in cell mediated immunity in influenza?

A

Antibody and cell mediated immunity in influenza

Infection induces antibody and cytotoxic T cell (CTL) response
Antibody recognises viral haemagglutinin and neuraminidase
High levels of CTL activity correlates with reduced viral shedding
Epidemics arise due to new strains not recognised by antibody (vaccine strains…….)

34
Q

How does HIV impact immunity

A

Attacks specific immune system
Targets CD4 T cell, macrophages and dendritic cells
Progressive development of AIDS leads to opportunistic infections

35
Q

List examples of opportunistic infections that arise from HIV

A

Oral candidiasis
Kaposi’s sarcoma
Pneuomcystis pneumonia

36
Q

Why can’t we develop vaccines against HIV?

A

Antibodies do not seem to impact HIV

37
Q

Can infections be controlled by cytotoxic T cell responses?

A

Potentially
Patients with higher levels of CTL activity show slower disease progression
Virus mutations that escape CTL recognition may lead to progression to AIDS

38
Q

Describe SARS-COV-2 RNA?

A

22-32 kilobase ss +ve RNA

39
Q

What sort of Ig response can helminths induce?

A

IgE

40
Q

What is the role of IgE

A

Mast cell mediated inflammation
Eosinophil ADCC (antibody-dependent cell-mediated cytotoxicity)

41
Q

Why are cytokines important in a response against parasites?

A

MQ activation as some protozoa can survive in MQ hidden from Ig

42
Q

Can differences in T cell responses result in different disease progression?

A

Yes

43
Q

What elements of the T cell response is active in C57BL/6 mouse that allows it to survive Leishmania?

A

TH1

44
Q

What elements of the T cell response is present in BALB/c mouse that allows it to succumb to Leishmania?

A

TH2 response

45
Q

What are the different effector mechanisms that are active at different stages during malaria?

A

Sporozoite and merozoite may be susceptible to antibody
Antibody may also kill infected red blood cells
Cytotoxic T cells active against infected liver cells
(RTS,S vaccine since 2019)

46
Q

What is ADCC

A

Antibody dependent cell cytoxicity

47
Q
A