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Immunology > Lec 2: Arms of the Immune System > Flashcards

Lec 2: Arms of the Immune System Flashcards

1
Q

Innate Immunity

A

Recognition of molecular motifs with invariant non-rearranging receptors

similar or same response each time

fast (within minutes or hours)

all cells mount innate responses to varying degrees, epigenetic changes to increase the robustness of the initial respose can act as a “memory” sort of

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2
Q

Adaptive immunity

A

recognition of antigens with receptors that rearrange for enhanced specificity

improved response to repeat exposure

SLow (5-6 days)

has memory and is mediated by B and T cells

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3
Q

Adaptive immunity may be divided into what two catagories

A

Humoral immunity = B cells, and the production of antibodies

Cellular Immunity = T cells, these kill cells and direct the adaptive immune response

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4
Q

Why does the magnitude and speed of the immune respose increase with repeated exposure

A

Adoption and increase of specificity of an antibody to a specific antigen

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5
Q

Tolerance

A

The B and T cells which are selected for are non-responsive// weakly respoinsive to the cells// antigens of the host

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6
Q

Plasma proteins are also known as

A

reactive proteins

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7
Q

serum is

A

the non clotting and a cellular component of the blood

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8
Q

Intrinsic immunity

A

Sub-catagory of the innate immune system

innate immunity can be activated, but intrinsic immunity is always present

consituitvely passive immunity in most cells of the body, but expression is enhanced by innate immunit signalling

basal expression is independent of IRF3, STAT1 and IFN signalling

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9
Q

restriction factors

A

cellular proteiins that directy restrict pathogen replication and assembly

clotting factors and bacteria for example

intrinsic immunity

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10
Q

Antimicrobial peptides

A

part of intrinsic immunity

these are built into mast cells and exhibit antimicrobial activity towards bacteria, viruses and fungi

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11
Q

What does it mean when you say that the innate immunity is non-specific

A

It means that innate immunity only recognizes components of a given pathogen

ex// the cell wall of S. aureus, not the microbe it’self

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12
Q

What PRRs are the innate immune system mediated by

A 
Toll like receptors (TLRs)
RIG like receptors (RLRs)
Nod like recep[tors (NLRs)
C-type lectin receptors (CLRs)
Orphan receptors
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13
Q

Which cell is the important link between the innate immune system and the adaptive immune system

A

Dendridic cell

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14
Q

Which transcription factors activate the innate immune system

A

Interferon response factors (IRFs)

Nuclear factor kappa B (NF-kB)

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15
Q

PAMPs

A

Pathogen associated molecular patterns

Bacterial or viral proteins
Bacterial or viral DNA
Viral RNA
Foreign glycans
Toxins
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16
Q

DAMPs

A

Damage associated molecular patterns

Location is super important, not just the signal

Damaged cells
Intracellualr host proteins
Host RNA, DNA and purine metabolites in the wrong compartment

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17
Q

Which TLR does peptidoglycan bind to

A

TLR2

Gram positives

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18
Q

Which TLR does Lipoteichoic acid bind to

A

TLR2
TLR6

Gram Postives

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19
Q

Which TLR does Lipopolysaccharide bind to

A

TLR4

Gram negatives

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20
Q

Why might TLRs be on cell surfaces

A

TLRs might be on a cell surface because it allows recognition before a cell is infected, or allows for the identification of microorganisms that only infect or colonize surfaces of cells

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21
Q

How do TLRs detect cololonization on the outside of the cell

A

leusine rich repeats

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22
Q

TIR Domain

A

Dimer formed by TLR and PAMP on the initial protein adapter on the cytoplasmic domain

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23
Q

WHy might TLRs be in endosomes

A

For engulfment of bacteria or when infected with a virus

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24
Q

What is triggered by PRR activation

A

IFNs
ISGs
Proinflammatory cytokines

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25
Q

IFNs

A

Interferons
(IFNa, IFNb, IFNg)

antiviral cytokines that elicit the activation of hundred of downstream genes for cellular protection against pathogens

26
Q

ISGs

A

Interferon-stimulated genes

Hundreds of host genes for cellular protection against pathogens

THis includes restriction factors

27
Q

Pro-inflammatory cytokines

A

promotes an inflammatory response and recruits immune cells

NFkB

28
Q

What is convergent signalling

A

the combination of both a DAMP and a PAMP, this leades to a stronger response

29
Q

What is the “clean up crew”

A

neutrophils and macrophages

30
Q

What is the “army”`

A

T and B cells

31
Q

Primary lymphiod organs

A

where immune cells develop (such as T and B cells)

Bone marrow and the Thymus

32
Q

Secondary lymphoid organs

A

where the adaptive immune responses are initiated

33
Q

What type of immunity do T cells play a role in, and where do they mature

A

They play a role in cell-mediated immunity and they mature in the thymus

34
Q

Helper T cells

A

CD4+
secrete immunoregulatory protiens called cytokines

Help to activate other effector cell types

35
Q

Cytotoxic T cells

A

CD8+
Kill virus-infected cells
Kill tumour cells

36
Q

What type of immunity do B cells play a role in, and where do they mature

A

B cells are involved in humoral immunity and they mature in the bone marrow

37
Q

Can T and B cells become long-lived memory cells?

38
Q

What does an activated B cell transform into

A

a plasma cell

39
Q

Plasma cells

A

secrete antibodies that bind to specific pathogens

antibodies can be used by other cell types to detect pathogens

antibodies can coat and neutralize pathogens

40
Q

BcR

A

immunoglobulin
Igg
B cell receptor

recognizes macromolecules (proteins, lipids, polysaccharides and other large chemicals) in linnear or conformational motifs

41
Q

TcR

A

T cell receptor

recognizes MHC-peptide complexes

They do NOT recognize free peptides, and weakly recognize free MHC

Antigen binding site contains hypercariable regions such that ther is one antigen recognition site/ TcR

42
Q

MHC

A

Major histocompatibility complex
aka (HLA)

found on APCs and recognize peptides

43
Q

MHC 1

A

present on all cells of the body

present peptides from inside the cell normally 8-10 aa in length

44
Q

MHC 2

A

present on antigen presenting cells and is presented to T-cells

peptides can come from inside the cell but they normally recognize extracelluar peptides 13-17 aa in length

note these peptides unlike the MHC 1 class of recptors allow the peptide to stick outside of the peptide cleft

45
Q

Why are dentridic cells so important

A

They express almsot all PRRs!

they can also travel from the skin and mucosal surfaces to the lymph nodes!

This means they are excellent for sampling tissues and activating t cells

Dendridic cells detect incoming pathogens, digest and present peptide antigens to T cells in lymph nodes (ACTIVATION)

46
Q

what are the best antigen presenting cells in the body

A

dentridic cells

47
Q

where are dendritic cells usually found

A

skin and mucosal surfaces

48
Q

Why are dendritic cells considered a part of the innate immune system

A

dendritic cells express many PRRs for detection of pathogens

49
Q

Why are dendritic cells considered part of the adaptive immune system

A

Activated dendritic cells will active T cells

50
Q

How do dendritic cells activate T cells

A

presentation of antigens from microbes on MHC molecules

Co-stimulation of T cells

Secretion of immunomodulatory proteins called cytokines

51
Q

what happens when a T cell effectors activates a T-cell

A

once activated, T-cells expand (clonal expansion) and divide to modulate an immune response

army recruitment

52
Q

CD4+ T cells activate other types of immune effector cells

A

Helper CD4+ T cells direct immune responses via cytokine and chemokine production

53
Q

cytokine

A

immune modulatory soluble protein

54
Q

Chemokine

A

chemotaxis-inducing cytokine

55
Q

B cell receptors vs antibodies

A 
BcR= surface
antibodies = soluble

the antigen binding site of BcR is hypervariable, thus is contains two antigen recognition sites

antibodies are secreted are secreted and do not contain transmembrane regions and cytoplasmic tail

56
Q

How do B cells Present antigens on MHC 2 molecules?

A

B cells recognize intact (not processed) antigen trapped on the surface of follicular dendritic cells

this is the first stage of B cell activation via BcR stimulation

once activated, B cells become antigen presenting cells (on an MHC ) and clonally expand via T cell stimulation

57
Q

Cognate B cell activation via a CD4+ Helper T cell

A

B cell is activated and clonally expands

This leads to the production fo antibody-producing plasma cells, germinal center B cells and memory B cells

58
Q

How is exquisite specificity to an antigen achieved

A

Via the myriad of BcR and TcR of variable regions

each recognize a single peptide

and binding of antigen stimulated a conformational change and receptor clustering that activates downstream signalling via the cytoplasmic tails

59
Q

What is the difference in the way that Tand B cells recognize antigens

A

T-cells recognize antigens via MHC II receptor - pepdite complex binding to TcR whereas B cells recognize free antigen via BcR ??

60
Q

Genetic determinants of host susceptibility to infection

A

Immune systems wotk on similar processes but are different (reason = SNPs)

Gene products often alter host suseptibility

  • mutations/ SNPs in cellular cell surface receptors
  • Mutations/ SNPs in innate and adaptive immune pathways
  • Mutations/ SNPs in tissue remodeling and repair
61
Q

Can you give an example of a mutation that alters immune capacity

A

Mutations in signal transduction cascades involved in damage and repair

Immunology (23 decks)

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