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

Lec 2: Arms of the Immune System Flashcards

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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
IFNs
Interferons (IFNa, IFNb, IFNg) antiviral cytokines that elicit the activation of hundred of downstream genes for cellular protection against pathogens
26
ISGs
Interferon-stimulated genes Hundreds of host genes for cellular protection against pathogens THis includes restriction factors
27
Pro-inflammatory cytokines
promotes an inflammatory response and recruits immune cells NFkB
28
What is convergent signalling
the combination of both a DAMP and a PAMP, this leades to a stronger response
29
What is the "clean up crew"
neutrophils and macrophages
30
What is the "army"`
T and B cells
31
Primary lymphiod organs
where immune cells develop (such as T and B cells) Bone marrow and the Thymus
32
Secondary lymphoid organs
where the adaptive immune responses are initiated
33
What type of immunity do T cells play a role in, and where do they mature
They play a role in cell-mediated immunity and they mature in the thymus
34
Helper T cells
CD4+ secrete immunoregulatory protiens called cytokines Help to activate other effector cell types
35
Cytotoxic T cells
CD8+ Kill virus-infected cells Kill tumour cells
36
What type of immunity do B cells play a role in, and where do they mature
B cells are involved in humoral immunity and they mature in the bone marrow
37
Can T and B cells become long-lived memory cells?
yessir
38
What does an activated B cell transform into
a plasma cell
39
Plasma cells
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
BcR
immunoglobulin Igg B cell receptor recognizes macromolecules (proteins, lipids, polysaccharides and other large chemicals) in linnear or conformational motifs
41
TcR
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
MHC
Major histocompatibility complex aka (HLA) found on APCs and recognize peptides
43
MHC 1
present on all cells of the body present peptides from inside the cell normally 8-10 aa in length
44
MHC 2
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
Why are dentridic cells so important
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
what are the best antigen presenting cells in the body
dentridic cells
47
where are dendritic cells usually found
skin and mucosal surfaces
48
Why are dendritic cells considered a part of the innate immune system
dendritic cells express many PRRs for detection of pathogens
49
Why are dendritic cells considered part of the adaptive immune system
Activated dendritic cells will active T cells
50
How do dendritic cells activate T cells
presentation of antigens from microbes on MHC molecules Co-stimulation of T cells Secretion of immunomodulatory proteins called cytokines
51
what happens when a T cell effectors activates a T-cell
once activated, T-cells expand (clonal expansion) and divide to modulate an immune response army recruitment
52
CD4+ T cells activate other types of immune effector cells
Helper CD4+ T cells direct immune responses via cytokine and chemokine production
53
cytokine
immune modulatory soluble protein
54
Chemokine
chemotaxis-inducing cytokine
55
B cell receptors vs antibodies
``` 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
How do B cells Present antigens on MHC 2 molecules?
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
Cognate B cell activation via a CD4+ Helper T cell
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
How is exquisite specificity to an antigen achieved
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
What is the difference in the way that Tand B cells recognize antigens
T-cells recognize antigens via MHC II receptor - pepdite complex binding to TcR whereas B cells recognize free antigen via BcR ??
60
Genetic determinants of host susceptibility to infection
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
Can you give an example of a mutation that alters immune capacity
Mutations in signal transduction cascades involved in damage and repair

Immunology (23 decks)

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