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human biochemistry > antibodies > Flashcards

antibodies Flashcards

1
Q

where do the immune system cells start

A

in the bone marrow

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2
Q

where do different immune cells go

A

to diff parts of body

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3
Q

the immune system is made up of what

A

a bunch of cells

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4
Q

immune memory comes from which cells

A

slow response cells

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5
Q

what is innate immunity

A

rapid response

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6
Q

what is adaptive immunity

A

slow response

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7
Q

name some innate immunity cells

A

macrophages

dendritic cell

mast cell

natural killer cell

complement protein

granulocytes:
- neutrophil
- eosinophil
- basophil

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8
Q

name some adaptive immnity cells

A

B cell - antibodies

T cell:
- CD4+ T cell
- CD8+ T cell

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9
Q

what cells are a mixture of adaptive and innate immunity

A

natural killer T cell

T cell

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10
Q

All cells of the immune system share what

A

share a common progenitor– the hematopoietic stem cell

Multipotent

(Multipotent cells become a certain group of cells , such as only becomes immune cells )

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11
Q

Rounds of differentiation and specialisation to cells produce

A

the vast array of ”white blood cells” that make up our immune system

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12
Q

The Lymphoid Lineage all start life where
doing what

A

in the bone marrow
receiving signals from stromal cells
such as T cells, B cells, and NK cells

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13
Q

where are T cells mature

A

Mature in the Thymus

Regulatory and Cytotoxic

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14
Q

where are B cells mature and what do they produce

A

Mature in the Bone Marrow
Produce antibodies

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15
Q

where are NK cells mature

A

Mature in the Bone Marrow, but also secondary lymphoid tissues

Cytotoxic

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16
Q

what is B cell development dependent on

A

on the transcription factor Pax5

In Pax5-/- mice, these progenitor B-cells can be transformed into T-cells and myeloid cells, suggesting that Pax5 is important for commitment to the B-cell development pathway.

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17
Q

what does The development of the B-cell, and thus the B-cell receptor, involve

A

a complex series of gene recombination to produce the vast array of antibodies we need

B cells make antibodies
Pax5 make b cells

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18
Q

how long roughly do antibodies take to develop

A

days to weeks

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19
Q

what is the instructive theory of antibody development

A

Linus Pauling -1940

The antigen acts as a template that directs the folding of the unfolded antibody chain

Thus, a specific amino acid chain has the propensity to form a variety of antibodies, depending on the antigen present at the time

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20
Q

what is the selective theory of antibody development

A

Macfarlane Burnet, Niels Jerne, David Talmage, and Joshua Lederberg – 1950s

The binding site of the antibody is already pre-determined before antigen is even encountered

The presence of antigen only affects how much of that specific antibody you get

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21
Q

name the 2 theorys of antibody development

A

instructive theory

selective theory

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22
Q

explain what the instructive theory would suggest

A

would suggest that if the antibody protein was unfolded and then refolded without antigen present it would lose its affinity.

7M Guanidine Hydrochloride an antibody against DNP-BSA was denatured
- DNP-BSA – highly immunogenic and useful for making antibodies to study

No affinity for DNP-BSA

7M Guanidine Hydrochloride is removed and the antibody re-folds

Addition of DNP-BSA shows the antibody continues to have affinity

Thus, the instructive theory was incorrect, and the binding of antigen is dependent on the amino acid sequence

23
Q

explain the selective theory of antibody development

A

Each antibody producing cell makes a single kind of antibody, and this commitment is determined before antigen is even present

Each cell has a distinctive base sequence in its DNA that determines the amino acid sequence

As the cell matures, each antibody producing cell makes a small amount of cell surface-bound antibody. The cell is then killed if it binds to a molecule during foetal development – therefore preventing B-cells that act against self

Later, the mature cell is activated and begins to undergo clonal expansion when exposed to antigen

Heterogeneous cell population = heterogeneous antibodies

These clones then persist long after the disappearance of the antigen

24
Q

name the different classes of antibody

A

IgA
IgD
IgE
IgG
IgM

25
Q

describe the properties of IgA

A

found in mucous, saliva, tears, and breast milk, and gut.

protects against pathogens

26
Q

describe the properties of IgD

A

part of B cell receptor

activates basophils and mast cells

alos are important for certain granulocytes to release those granules

27
Q

describe the properties of IgE

A

protects against parasitic worms

responsible for allergic reactions

28
Q

describe the properties of IgG

A

secreted by plasma cells in blood

able to cross the placenta to the foetus

29
Q

describe the properties of IgM

A

Antibodies start life as igm

may be attached to the surface of a B cell or secreted into the blood

responsible for early signs of immunity

30
Q

know the polypeptide structure

A

see image notes for help

its a Polypeptide as antibodies are proteins

31
Q

in antibody structure what does Fab stand for

A

Antigen binding Fragment

its the top part of the structure

32
Q

in antibody structure what does Fc stand for

A

Crystallisable region fragment

its the bottom part of the structure

33
Q

describe the IgG antibody structure

A

Made up of 2 polypeptide chains:
- Light Chain
- Heavy Chain
- H2L2

Held together by disulphide bridge

Both chains consist of a variable region and a constant region:
- Variable = is between 1 – 108 amino acids
- Constant = 109 – C-terminus

34
Q

VL and VH are very similar on what antibody

A

the same antibodies

35
Q

what does the heavy chain consist of

A

consists of 3 equal thirds

CH1, CH2, and CH3 are very similar to each other

36
Q

CL is very similar to what other domains

A

3 CH domains

37
Q

The intrachain disulphide bond is located where on antibodies - homologous domains

A

in the same place on every domain of both the H and L chains

38
Q

explain antibody immunoglobulin folding

A

Broad sheets of anti-parallel β-sheets
- Hydrophobic side chains are tightly packed between the sheets and held together with disulphide bridges

39
Q

explain the constant and variable domains after antibodies immunoglobulin folding

A

Constant domains
- 3 β-sheets in one strand and 4 on the other

Variable domains
- 2 additional β-sheets
3 loops that compose the part of the antigen binding site, and are highly variable

40
Q

what does translocation of gene mean

A

part of gene cut off and moved somewhere else

41
Q

explain what 1965 – William Dryer and Claude Bennett
predicted about antibody diversity

A

Multiple Variable genes

1 Constant gene

These genes are separated, and one V becomes joined to the C during differentiation and maturation of the B-cell

42
Q

explain what 1985 – Susuma Tonegawa confirmed about antibody diversity

A

Confirmed that V and C genes are far apart in the embryonic DNA and closely associated in B-cells

Immunoglobulin genes are translocated during the differentiation of B-cells

43
Q

what is The number of different kinds of antibodies that can be made by an animal
give ex

A

in the millions

ex: Mouse
Several hundred genes for variable regions
~300 for the light chain
~300 for the heavy chain
That leads to 9x104 different specificities

44
Q

there is a large discrepancy between the germline variation and adult variation, so there must be what generated

A

an ternate source generated during the lifetimes of an animal and the differentiation of its lymphocytes

45
Q

explain V(D)J Recombination

A

The V gene does not encode for the entire polypeptide chain.
- Stops at amino acid 95
- 13 residues too short, as amino acid chain is 108 amino acids long

Light Chain:
The stretch of DNA that encodes for this region is found nearer the Constant region
An array of 4 J regions:
- J = Joining as it joins the V and C regions
- Encode part of CDR3

1 of the several hundred V genes can become spliced to one of the 4 J genes
- Further diversity added as this splicing can occur in different joining frames

Heavy Chain:
The heavy chain has an additional region – the D region
- D = Diversity region
- 15 genes within this region
- A D gene will splice with a J gene, which will then become spliced with one of the V genes

The enzyme deoxyribonucleotidyl transferase, a special polymerase that does not use a template, inserts extra nucleotides between the V and D regions

46
Q

how many possible variations of antibody combinations are there when we look at the light and heavy chains

A

Light Chain:
- ~250 V genes
- 4 J genes
- At least 3 possible joining frames
- 250 x 4 x 3 = 3000 possible variable combinations

Heavy Chain:
- ~250 V genes
- 5 J genes
- 15 D genes
- At least 3 possible joining frames
- 250 x 5 x 15 x 3 = 56,250 possible variable combinations

3000 x 56,250 = 1.7x108 possible variations of antibody combinations

47
Q

explain Class Switch Recombination

A

B-cells begin life producing only IgM
- Class Switching recombination is needed to produce the other types of antibody

The constant regions of the heavy chains vary

Different classes of heavy chains depending on the antibody type:
- G – γ
- M - µ
- A – α
- D - δ

48
Q

Somatic Hypermutation results in mutations being introduced into what region

A

into the V region of the heavy chain and light chain, altering the affinity of the immunoglobulin for its antigen

49
Q

in Class Switch Recombination, the initial heavy‐chain C regions are replaced by what

A

another isotype, modifying the effector activity of the immunoglobulin but not its specificity.

50
Q

somatic hypermutation and class switch recombination occur where as what

A

occur in secondary lymphoid tissues as part of the Germinal Centre reaction

Requires other cell types:
- CD4+ T-cells
- Dendritic Cells
- Produces long lived plasma cells that produce antibodies with a high affinity for the target antigen

51
Q

in the The Germinal Centre reaction what makes the dark zone darker

A

more cells that it has

52
Q

what happens to many B cells from the The Germinal Centre reaction

A

they dont grow or change but just exist

53
Q

what cells produce the high affintity antibodies

A

Long lived plasma cells

54
Q

name some practical uses of antibodies

A

Staining:
- Microscopy
- Flow Cytometry
- Western Blotting

Antigen Capture:
- ELISA – measures how
much of a protein you have in a sample

Drugs:
- Highly specific to the target, so reduced off-target effects
- ex Chemotherapy

human biochemistry (10 decks)

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