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2 Immunology > Specific Immunity > Flashcards

Specific Immunity Flashcards

(100 cards)

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1
Q

Describe the structure of an antibody?

A

Variable and constant region, heavy chain and light chain

Variable region is the part that has antigen specificity, made of heavy chain on the medial side and light chains on the lateral sides.

Constant region determines the class and function of the antibody, made of light chain outside and heavy chains inside

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2
Q

List the. Alist the 5 classes of antibodies

A 
IgA
IgD
IgE
IgG
IgM
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3
Q

List the two variants of light chains

A

Kappa and lambda

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4
Q

List the 5 variants of heavy chain

A 
Mu
Alpha
Delta
Echilon
Gamma
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5
Q

Constant regions can change without affecting the variable region, T or F?

A

True. Antigen specificity can remain the same while undergoing class switching

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6
Q

How does a neonate receive antibodies? What classes?

A

IgA through breast milk

IgG through placenta

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7
Q

Which immunoglobulins are able to activate complement?

A

IgM and IgG

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8
Q

Which immunoglobulin activates mast cells?

A

IgE

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9
Q

List mechanisms allowing for variation in antibody specificity arises

A

VDJ or VJ recombination

Junctional diversity

Somatic hypermutation

Isotype class switching

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10
Q

Explain VDJ recombination

A

The variable portion of antibodies are coded in the genome from 3 regions (V)ariable, (D)iversity, and (J)oining.

Heavy chains are coded from VDJ while light chains are coded from VJ regions

Each region has multiple types, which can be combined in many permutations to form a chain.

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11
Q

Explain the process of junctional diversity

A

During recombination, genes are recombined via hairpin loop formation or coiled gene formation.

After cleaving and splicing, the imprecision of which allows for new random nucleotides to be added in between regions, giving more diversity.

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12
Q

What is the role of RSS - recombination segment sequence

A

Each V or J or D segments are flanked by an RSS segment, RSS segments attached to V segments have 12bP while RSS segments associated with J segments have 23 bP

The 23/12 rule ensures that segments from V segment will join to another J segment, this prevents the scenario where 2 V segments join together.

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13
Q

What is the protein that adds random nucleotides between segments?

1) ARTEMIS
2) RAG 1
3) Ligase
4) TdT
5) DNA polymerase II

A

Terminal deoxynucleotidyl transferase (TdT)

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14
Q

What type of antigens can induce T-independent B cell activation?

A

Polysaccharide, carbohydrate based antigens.

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15
Q

What kind of antibodies are made in T-independent B cell activation?

A

Mostly IgM

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16
Q

Explain the process of T-dependent B cell activation

A

B cell engulfs pathogen with and presents specific antigen w/ MHC II

T cell which has been activated by the same antigen find the corresponding B cell and activates the B cell via TCR - MHC II - peptide binding.

T cells also express CD40L as a costimulatory molecule, binding to CD40 on the B cell.

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17
Q

What is the costimulatory molecule that T cells express to activate B cells>

A

CD40L

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18
Q

Which MHC class molecule do B cells present antigen with?

A

MHC II

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19
Q

Which receptor does a T cell use to recognise activated B cells?

A

T cell receptor, bind with specific antigen associated w/ MHC class II

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20
Q

What happens after a B cell is activated by a T cell?

A

It causes class switching and/or proliferation of the B cell, somatic hypermutation also occurs.

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21
Q

Where do activated B cells go to?

A

Germinal center in the lymph node

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22
Q

Explain somatic hypermutation

A

With each division of B cells, the tightness of the antibody binding to antigen varies, in somatic hypermutation, only the strongest fitting antibodies are given the proliferation signal, thereby eliminating weak binding antibodies.

I.e. Affinity maturation

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23
Q

What type of cells can an activated B cell become?

A

Plasma cell

Or

Memory B cell

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24
Q

What does a plasma cell do?

A

Make and secrete large amounts of antibodies.

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25
How does isotype class switching happen?
By cleaving gene segments from an antibody, constant regions can change.
26
What is the first type of antibody made?
IgM
27
Class switching is reversible, true or false?
False. They can only go in 1 direction
28
What controls class switching?
Cytokine environment, T cell directed.
29
Which chromosome is MHC/HLA coded on?
Chromosome 6
30
What are the MHC variants for class I MHC?
HLA-A HLA-B HLA-C
31
What are the MHC variants for class II MHC?
HLA-DP HLA-DQ HLA-DR
32
What is the inheritance pattern for MHC genes?
We inherit 1 of each MHC subtypes from each parent I.e. For MHC Class I we have HLA-A (mom) & HLA-A (dad) HLA-B (mom) & HLA-B (dad) HLA-C (mom) & HLA-C (dad) Same for MHC Class II
33
What is the consequence of polymorphic genes in MHC class
Means that each gene can have variations between populations by up to 20aa -> giving more diversity
34
What is the important of having MHC diversity?
To prevent a single pathogen which has managed to evade an binding to an MHC type to erradicate the entire population.
35
What cells express MHC I?
``` T cells B cells Macrophages Neutrophils Other APCs Thymic epithelial cells Other nucleated cells ```
36
What cells express MHC Class II?
``` Activated T cells B cells Macrophages Other APCs Thymic epithelial cells ```
37
MHC Class I is more widely expressed T or F?
True - it is expressed on all nucleated cells.
38
Describe the structure of an MHC molecule
Made of 2 polypeptide chains Consist of alpha chain and beta chain. Consists of peptide-binding cleft
39
What chain makes up the peptide-binding cleft of an MHC molecule?
Alpha 1 and alpha 2
40
What chains form the membrane binding site of an MHC molecule?
Alpha 3 and beta2
41
CD4 cells recognise MHC Class II, true or false?
True, CD4 cells are activated by antigen bound to MHC Class II
42
What MHC class does CD8 bind to
MHC class I
43
What is the difference between the cleft of MHC I and II?
class II has a larger cleft, accomodating larger antigens.
44
If MHC class I molecules are found widely on most cells, how is it that NK cells can be activated?
``` MHC class I inactivateds NK cells But in virally infected cells, they stop expressing MHC class I, allowing the NK cells to be activated by other mechanisms ```
45
Which MHC class is more widely found?
MHC Class I
46
What is the role of a memory B cell
To initiate rapid response to a pathogen encountered before.
47
What is an epitope?
The part of the antigen that the antibody attaches to
48
What is the difference between affinity and avidity in terms of antibody binding?
Affinity is the strength of interaction between each single points of binding Avidity is the combined total strength of binding among all sites of binding. E.g. IgM has 10 weak binding sites for antigen while IgG, IgE and IgD have 2 stronger binding sites. Therefore IgM has low affinity, but high avidity.
49
B cells are also antigen presenting cells - true or false?
True, B cells are involved in engulfing pathogens and re-presenting their antigens on MHC Class II for CD4 t cells to find.
50
What is the meaning of clonal selection?
The activation of a particular B cell with its specific antibody and the subsequent proliferation of that B cell and antibody.
51
What is CD3?
CD3 is expressed in all T cells, it is the definition of a T cell. is it part of the T-cell receptor complex
52
What are the 4 subclasses of CD4 T cells
TH1 TH2 TH17 and TReg
53
What do TH1 cells do
Help eradicate pathogens infecting macrophages intracellulary without killing the cell
54
Which CD4 subtype is involved in activating B cells
TH1 and TH2
55
What do TH17 cells do?
Activate fibroblast and epithelial cells during inflammation, help activate neutrophils
56
Which CD4 subtype helps activate neutrophils?
TH17
57
What is the role of TReg
Regulate immnune system after initiation, prevent autoimmune damage
58
What does CD stand for? 1) cluster of denomination 2) carriers of death 3) cluster of differentiation 4) compact disk 5) combination of differentiation
3) cluster of differentiation
59
What do CD8 t cells do?
Cytotoxic T cells, kill intracellulary infected cells via MHC Class I presented antigen - initiate apoptosis
60
Which T cell subtype expresses foxp3?
TReg
61
What chains is the TCR made of?
Alpha and beta chain, variable and constant regions.
62
Beta chains on TCR is made of VJ segments - true or false?
False Beta chain is analogous to heavy chain in BCR, it is made out of VDJ segments
63
TCR go through affinity maturation through the interaction of MHC Class I molecules - true or false?
False, TCR do not go through hypersomatic mutation
64
What does a T cell receptor complex consist of?
Alpha and beta chains making up constant and variable region CD3 co-receptors which help in intracellular signalling
65
Which T cell membrane protein acts as a second activation signal ?
CD4 and CD8 molecules which interact with either MHC I or MCH II
66
Explain how a CD8 cell is activated and its function
CD8 cell meets a dendritic cell presenting its antigen, DC cell makes IL-2 which induces proliferation in the CD8 cell. CD8 cell then goes to look for infected cell with the same antigen. Infected cell will have its antigen presented on an MHC I molecule. Once CD8 cell has found its antigen, it forms a link called a Supramolecular adhesion complex (SMAC), forming an immunological synapse between the two cells. The CD8 cell then induces apoptosis by releasing cytotoxic granules
67
Which interleukin stimulates a CD8 cell to proliferate?
IL-2
68
What is the name of the gap formed between a CD8 cell and its target?
Immunological synapse
69
What are the co-stimulatory molecules needed by a CD8 cell to become activated?
CD28 receptor on the CD8 cell | B7 ligand on the DC
70
What are the cytotoxic granules released by a CD8 cell
Perforin - makes a pore Granzymes - proteases Granulysin - induce apoptosis
71
Explain thymocyte maturation in the thymus
Lymphoid precursor cell goes from BM to thymus First it expresses both CD4 and CD8 + TCR = double positive thymocyte Then a thymic epithelial cell with either MHC I or MHC II will bind to the thymocyter, depending on which MHC class it binds stronger to, it will determine if it becomes CD4 or CD8. T cells are also exposed to the AIRE protein where it is selected for non-autoreactivity
72
MHC = HLA in humans, T or F?
T
73
What MHC class does an APC express?
MHC II
74
A T cell will become activated even if the APC MHC is not the same as the T cell MHC - T or F?
F, APC has to have the same MHC as the t cell, to ensure only host cells can activate host immune system
75
What happens if a T cell is shown its antigen but not a co-stimulatory signal?
The cell apoptises
76
What is the function of a co-stimulatory signal
To prevent rampant T cell activation, causing autoimmune diseases
77
What is the role of "danger signals"
Danger signals upregulate the expression of co-stimulatory signals (CD28 and B7)
78
CD28 is an antigen found on dendritic cells - T or F?
F, CD28 is a co-stimlation receptor found on T cells.
79
A memory T cell does not require co-stimulation to become activated - T or F?
True.
80
TH17 T cells help B cells class switch to IgE - T or F?
F, TH2 does that.
81
TReg cells help B cells to become activated - T or F?
F, Treg suppresses T cell responses
82
All subtypes of CD4 T cells have the ability to activate B cells - T or F?
F, only TH1 and TH2 do that
83
TH1 cells kill pathogens infecting macrophages intracellulary, using IFN-gamma
True. TH1 cells can erradicate pathogens within a macrophage, without killing the macrophage.
84
Which CD4 T cell subtype activates basophils and eosinophils?
TH2
85
Which Th cell activates fibroblasts and epithelial cells during inflammation?
TH17
86
Which Th cell helps to activate neutrophils?
TH17
87
Which interleukin induces T cell to become Th2 cell?>
IL-4
88
Which cytokine does T cell require to become TH1?
IL-12 and IFN-gamma
89
Which cytokine regulates Treg formation?
TGF-beta
90
Which cytokine inhibit TH1 and TH2 production?
TGF-beta
91
IFN-gamma inhibits TH2 proliferation - True or False?
True
92
What cytokines inhibit growth and activation of th1?
TGF-beta and IL-10
93
What cytokines does a TH2 cell produce to inhibit TH1 formation?
TGF-beta and IL-10
94
Which T cell subtype is involved in cell mediated immunity and opsonising antibodies?
Th1
95
Which form of leprosy has a high infectivity? Tuberculoid or lepromatous?
Lepromatous
96
Which t cell subtype is involved in tuberculoid leprosy?
Th1
97
What is CD16 involved in?
CD16 is a receptor found on NK cells. They are involved in antibody-dependent cellular cytotoxicity (ADCC) AKA FcGammaRIII
98
What is the role of CD40?
CD40 is a receptor found on B cells, activated by CD40-L which is found on T cells
99
IgA passed on from mother to baby through breast milk is absorbed by the lumen of the gut and enters the baby blood - T or F?
F, IgA stays in the gut coating the lumen.
100
What are the 3 subtypes of MHC Class II?
HLA-DP HLA-DQ HLA-DR

2 Immunology (3 decks)

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