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Immunology > Antibody > Flashcards

Antibody Flashcards

1
Q

What are the 2 fragments of antibody?
What are their functions?

A

Fragment Ag binding ( Fab )
-> Antigen binding ==?

Fragment crystallizable ( Fc )
-> Complement activation
-> FcR binding ( Fragment crystallizable Receptor )

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2
Q

Is it true that antibody is a tetramer?

A

Yes

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3
Q

What is the hinge in antibody?
What is its function?

A

Its between Fab & Fc
-> Allows opening / closing & twisting of Fab for better antigen binding

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4
Q

What do the following do to antibodies?
-> Pepsin digestion
-> Mercaptoethanol reduction
-> Papain digestion

A

Pepsin digestion
-> Cuts right below hinge
- -> F(ab)2 x1

Mercaptoethanol reduction
-> Breaks every disulfur bond
- -> H chain x2
- -> L chain x2

Papain
-> Cuts right above hinge
- -> Fab x2
- -> Fc x1

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5
Q

What does CDR 1, 2, 3 spikes in variability?

A

CDRs are the sites for antigen binding
-> Higher variability = more diversity for different antigen

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6
Q

What is the other region other than CDR region on an antibody?
What is its function?

A

Framework region
-> provides structural support

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7
Q

Does the top part of the variable segment or the bottom part of constant segment carries NH+ / COO- on an antibody?

A

Top part of V segment
-> NH+

Bottom part pf C segment
-> COO-

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8
Q

What are the 3 components of BCR?

A

BCR
-> mIg
-> CD79 ( Ig - alpha + Ig - beta ) x2

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9
Q

Is CD79 ( Ig - alpha / Ig - beta ) a B cell specific marker for cell identification?

A

YEET

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10
Q

Which 2 antibody classes are found on BCR membrane?

A

IgM & IgD

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11
Q

Which 2 antibody classes have an additional domain on their heavy chain C segment?

A

IgM, IgE

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12
Q

Are immune complex reversible?
why?

Immune complex: The state of Ag - Ab

A

Yes
-> Non covalent bonds = reversible

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13
Q

Which antibody class is mainly in mucosal transport?

A

IgA

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14
Q

Which antibody class is responsible for acute allergies?

A

IgE

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15
Q

Which antibody class dominates other classes in terms of number in circulation?
Why?

A

IgG
-> Higher half - life

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16
Q

Is IgM or IgD better at activating complements?

A

IgM

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17
Q

A woman & her fetus is infected by bacteria, what is the order for antibodies to cross the placenta and save DA BABY?

A

IgG
-> Only IgG can cross placenta

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18
Q

Match the following <:

mIgM
sIgM Monomer
IgD
IgG Dimers
IgE
IgA Pentamer

A

Monomer
-> mIgM
-> IgD
-> IgG
-> IgE

Dimer
-> IgA

Pentamer
-> sIgM

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19
Q

We learned about TCR - CD3
What about BCR - CD??

A

CD79

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20
Q

Explain first contact & second contact of allergy using the example of pollen

A

First contact with antigen ( Low level immune response )
-> CD79 activates naive B cell => Plasma cell
- -> Secretion of IgE
- - -> IgE attaches to Mast cells

Second contact with antigen ( Supaa high level immune response )
-> IgE on Mast cells grabs antigen
- -> Activation on Mast cell
- - -> Releases granules containing Histamine
- - - -> Allergic reaction

21
Q

Where is pIgR found?
What is its purpose?

A

Mucosal epithelium
Function
-> To transport polymeric Ig across the mucosal epithelium to the mucosal surface
-> To offer protection & stability to polymeric Ig

22
Q

What are the steps for secreting IgA from plasma cell in submucosa to the lumen?

A

Binding of dimeric IgA by pIgR
-> Endocytosis of IgA into mucosal epithelium in cytosolic vesicle
- -> Enzymatic cleavage of pIgR
- - -> Secretory IgA + pIgR

23
Q

Secretion & composition of colostrum & milk

Match the predominates antibody class ( IgG, IgA ) to the following

Ruminants colostrum
Ruminants milk
Non ruminants colostrum
Non ruminants milk
Primates colostrum
Primates milk

A

Ruminants
-> IgG

Non ruminants colostrum
-> IgG

Non ruminant milk
-> IgA

Primates
-> IgA

24
Q

What are the 4 reasons why antibodies can be absorbed and not be digested in newborn’s stomach?

A

Low protease activity
Trypsin inhibitors in colostrum
Special FcRs ( FcRn ) in intestinal epithelium
Permeability in intestine is highest
-> Declines after 6hrs
- -> FcRn+ => FcRn-

25
Q

Which body parts immunity do colostrum & milk provide in Ruminants ?

A

Colostrum
-> System immunity

Milk
-> Intestinal immunity

26
Q

Why aren’t vaccines useful for newborn?

A

Maternal antibody will neutralize antigen
-> B cell of newborn will not be activated

27
Q

What did IgY evolve into in mammals?

A

IgG
IgE

28
Q

Which antibody class is in egg white & egg yolk?

A

Albumin ( Egg white )
- IgA

Egg yolk
- IgY

29
Q

What is the 3 reasons why IgY is so shitty?

A

Poor in
-> Opsonization
-> Complement activation
-> Activating allergic response

30
Q

Why does IgY still exists then?

A

Extremely diverse environment meaning that not being too sensitive might actually be healthy for the animal
-> Being able to identify antigen without activating strong immunity is nice

31
Q

What is an opsonin?

A

Any molecules that targets an antigen for immune responses

32
Q

What is opsonization of antibody?

A

Allow binding of FcR of phagocytic cells to Fc for easier phagocytosis

33
Q

What is the classic pathway of complement activation?

A

Activation of C1 - complex

34
Q

What is the 3 antibody - mediated effector functions?

A

Opsonization
Activation of complement
ADCC

35
Q

What is isotypic determinants?

A

Difference in C segment of heavy chain
-> Antibody classes

C region determinants collectively determines the antibody class within a specices

36
Q

What is allotypic determinants?

A

Subtle a.a. difference in the same class
-> Different strain
- -> usually subtle, but might affect interactions with effector cells

Typically subtle
-> Still contributes to the general diversity of immunity between individuals in a species

37
Q

What is idiotypic determinants ( Idiotopes )?

A

Difference in V segment
-> Different antibodies ( essentially what we have been learning about diversity of antibodies )

Difference in antibody within an individual
-> Sum of the individual idiotopes = idiotype of antibody

38
Q

What are the 3 reason for B cell anergy?

A

Downregulation of mIgM
-> more than 5% of mIgM are occupied by monomeric soluble Ag
- -> Only mIgM
- - -> Not mIgD

B cell encountering antigen without the help of T cell

B cell unresponsive to antigen even with the help of T cell

39
Q

Are there more IgM / IgG produced in first contact / second contact?

A

First contact
-> IgM

Second contact
-> IgG

40
Q

What are the order for affinity ( Weakest to strongest ) for antibody class ?

A

IgM , IgD < IgG < IgE < IgA

41
Q

What are the 3 coreceptors (CD) for B cell activation?

A

CD81
CD21
CD19

42
Q

What is the coreceptor for B cell inhibitor?

A

CD22

43
Q

What does bcl - 2 do?

A

Prevents apoptosis ( Inhibits apoptosis )

44
Q

What does bax do?

A

Opposes bcl - 2 ( Promotes apoptosis )

45
Q

What does Fas do?

A

Induces apoptosis ( Initiates apoptosis )

46
Q

What is Idiotypic regulation?

A

When there is an immune response
-> Both idiotypic & anti idiotypic antibodies are produced
- -> Anti idiotypic antibodies can either inhibit / enhance idiotypic antibodies
- - -> This ensures the immune response is proportionate to the threat
- - - -> Prevent prolonged / excessive immune response
- - - -> Prevent inadequate immune response

47
Q

What is polyclonal antibodies?

A

Mix of antibodies produced by difference plasma cell
Recognizes various epitopes
Produced naturally by immune system to combat infections
Polyclonal antibodies can be derived from serum of animals

48
Q

What is monoclonal antibodies?

A

Identical antibodies with exact same VDJC segments
Highly specific & recognizing only 1 epitope
Produced by hybridoma cells
-> Plasma cells + Myeloma cells
(Myeloma cells : cancer cell originated from plasma cell)

Immunology (8 decks)

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