Immunology Chapter 6

Question 1

Let’s say
IgM 1 is from a human - recognize rabies
IgM 2 is from a human - recogmize SARs Cov

Why will the variable regions be different, and what region will be the most different?

Answer 1

Because they recognize different antigens

The difference will be mostly in the hypervariable region

Question 2

Let’s say
IgM 2 is from a human - recognize SARs Cov
IgM 3 is from a human - also recognize SARs Cov

Even though they recognize the same virus, the amino acid sequence in the variable regions will be a bit different

Why?

Answer 2

Because every B cell makes its unique version of the BCR

Question 3

Where are the two binding sites located

Answer 3

variable region

Question 4

Variable regions (V)

Answer 4

the N-terminal portion of both H and L chains that are different for different antibodies

Question 5

What are the two types of L chains in immunoglobulins

Answer 5

Kappa and Lambda chains

Question 6

What are the five types of H chains in immunoglobulins

Answer 6

Gamma, Mu, Delta, Epsilon, Alpha

Question 7

What determines the class or isotype of an immunoglobulin

Answer 7

type of H chain

Question 8

Can an Ig have both K and Lamba light chains

Answer 8

No, it can have either but not both

Question 9

Are γ2λ2 and γ2κ2 antibodies the same isotype? Why or why not?

Answer 9

Yes, because they have the same heavy chain, so they’re the same type

Question 10

The HV chain, contributes significantly to the antigen-binding region, and is part of the antibody that contacts the,…

Answer 10

antigen

Question 11

The BCR and Ab are composed of a series of

Answer 11

globular domains (Ig domains)

Question 12

Proteins that contain Ig domains are

Answer 12

BCR, Ab, TCR, MHC I, MHC II, CD4, CD8

Question 13

What is the role of Ig domains

Answer 13

immune responses, and cell-cell recognition in the immune system

Question 14

Hypervariable regions are also called

Answer 14

CDR

Question 15

Each globular domain consists of a β barrel made by

Answer 15

2 parallel β strands

Question 16

If you see a diagram, the grey parts are called framework region, what is the role

Answer 16

they form β strands and β sheets of the Ig domain, and they separate the CDR

Question 17

How many regions of HV (CDR) does H and L chains have

Answer 17

H: 3 HV regions
L: 3 HV regions

Question 18

So what determines the antigen specificity of the BCR / Ab

Answer 18

combination of CDRs

Question 19

Even if the Ab recognizes different viruses, and are from different people, the amino acid of the constant regions will be…

Answer 19

identical

Question 20

Why is it important that the constant regions stay the same

Answer 20

You can transfuse antibodies from one person to another

Convalescent plasma: Ab from someone recovered from a virus

IVIG: pooled Ig from healthy donor give to people who lack it

Question 21

Would the constant regions be the same if IgM 1 is from a dog, and IgM 2 is from a human, but they both recognize rabies

Answer 21

No, it would be different because they are the same species, and they are immunogenic

so antibodies from another species can be antigens for humans

Question 22

What happens if a person receives a transfusion of anti-rabies antibody from a dog

Answer 22

If the person has rabies virus, the antibody will bind to the virus and prevent infection

However, the person’s immune system will make antibodies against the dog antibodies because it is foreign (10 days)

This causes pain in joints and skin

Question 23

If a person has been bit by a rabid animal, is it worth getting the anti-rabies antibodies from a dog even if they will experience pain and discomfort about 10 days later?

Answer 23

Yes, because it saves the person in emergency and life-threatening conditions

Question 24

What are the structures that antibodies bind to

Answer 24

epitopes (antigenic determinants)

Question 25

What shape do epitopes have

Answer 25

3-d shape (not linear)

Question 26

How long are epitopes

Answer 26

4-5 amino acids long

Question 27

Do epitopes need to be amino acids

Answer 27

No, they can also be lipids, carbohydrates synthetic chemicals, etc

Question 28

Do antigens have more than one kind of epitope

Answer 28

yes

Question 29

Review: the peptide bound to MHC is what shape

Answer 29

linear

Question 30

When B cells first start secreting antibodies, what type do they always secrete first

Answer 30

IgM

Question 31

When B cells make an immunoglobulin class switching, what changes and what stays the same

Answer 31

Constant region of the heavy region change (CH) Vh, Lh, and CL remain the same

Question 32

Immunoglobulin class switching involves cutting out what

Answer 32

sections of DNA in the CH region

Question 33

What induces the class switching, and how?

Answer 33

T helper cells via cytokines

Question 34

How do we get a DNA of a naive B cell expressing IgM and IgD

Answer 34

run through transcription, then there is alternative RNA splicing

Question 35

How to we get a DNA of a naive B cell expressing IgG

Answer 35

we take the gene segments encoding IgM and IgD and we splice it A B cell that switches to IgG, will never make IgM or IgD again

Question 36

Different antibodies have different roles in the immune system -- this is determined by

Answer 36

C regions of the H chain

Question 37

The whole point of B cell activation is to get the plasma B cells to synthesize and secrete antibodies into the body fluids Whether an immunoglobulin is membrane bound on the B cell or secreted by the B cell depends on what region of the antibody

Answer 37

C-terminus end of the Constant region of the Heavy Chain (CH)

Question 38

What is Ab Neutralization

Answer 38

When Ab neutralizes the pathogen by binding to them, and preventing them from binding to the host cell

Question 39

Neutralization of a pathogen or toxin relies on what region of the antibody?

Answer 39

Variable

Question 40

Antibodies can be digested in vitro with what enzyme? and what is the results

Answer 40

Papain, fragments called Fab and Fc Fab fragments can still bind to the antigen

Question 41

What is Opsonization

Answer 41

the binding of antibody or C3b to a pathogen to enhance phagocytosis

Question 42

The biological function of opsonization of a pathgoen depends on which region of the antibody

Answer 42

constant region tpi yg di paling bawah

Question 43

Not all classes of antibodies can act as opsonin, what class does

Answer 43

IgG only

Question 44

How does opsonization increase the number of contact points between a pathogen and phagocytic cell

Answer 44

By coating the pathogen with an antibody or C3b, which can be recognized by receptors on the phagocyte

Question 45

What part of the antibody is recognized by phagocytic cells during opsonization

Answer 45

Fc region (Fc receptor)

Question 46

What receptors on phavocytic cells recognize C3b

Answer 46

Complement receptors (receptors of C3b)

Question 47

Why does opsonization make phagocytosis more efficient

Answer 47

Because it increases binding between the pathogen and the phagocyte, making it easier for the immune cell to engulf the pathogen

Question 48

What happens when an antibody binds to a pathogen's surface

Answer 48

activated the classical complement pathway

Question 49

What is formed on the pathogen membrane as a result of complement activation

Answer 49

the membrane attack complex (MAC)

Question 50

What is the first step in antibody and complement-mediated killing

Answer 50

antibody binds to pathogen, recruiting early complement proteins

Question 51

What enzyme complex is built after early complement proteins are recruited

Answer 51

C3 convertase

Question 52

After C3 convertase is formed in the classical pathway, what happens next?

Answer 52

The rest of the pathway continues the alternative pathway

Question 53

So explain the pathway starting from binding of antibody (soluble PRR) to pathogen, and the recruitment of early component proteins

Answer 53

C3 convertase cleaves C3 --> C3a + C3b C3b binds into something and form C5 convertase That cleaves C5 --> C5a + C5b C5b starts the MAC formation MAC goes into the pathogen membrane Pathogen lysis

Question 54

Which Ig type activates complement proteins

Answer 54

IgG and IgM

Question 55

Which Ig activates mast cells and cause allergy symptoms

Answer 55

IgE

Question 56

The biological function of complement activation depends on which part of the HEAVY CHAIN

Answer 56

Constant (tpi kyk tengah atas)

Question 57

IgA is an important antibody in protecting you against pathogens that you inhale and ingest. In mucus secretions, it exists as a dimer How many antigen-binding sites would this antibody have

Answer 57

4

Question 58

What is the name of the chain that holds the dimer together

Answer 58

J chain (Joining chain)

Question 59

What Ig is not secreted, and what is its function

Answer 59

IgD, acts as BCR to help signal B cells to become activated

Question 60

IgM has a unique shape, like a star, but not all its binding sites will be engaged, how many binding sites does it have

Answer 60

10

Question 61

IgG binds to FcR on

Answer 61

macrophages

Question 62

IgE binds to FcR on

Answer 62

mast cells

Question 63

What is the secretory component of IgA, and when is it added?

Answer 63

a protein added when IgA moves across epithelial cells into mucus

Question 64

What is the main function of IgA

Answer 64

Neutralization of pathogens

Question 65

What happens when a pathogen is bound by IgA in the respiratory tract?

Answer 65

It is swept out of the respiratory tract

Question 66

What happens when a pathogen is bound by IgA in the GI tract

Answer 66

It is coated with IgA and excreted through the GI tract (back door)

Question 67

Why is IgA especially important for breastfed infants

Answer 67

It helps protect them by neutralizing pathogens in the mucosal surfaces, supporting their early immune defense.

Question 68

What determines whether an antibody will bind to an epitope

Answer 68

The complementary shape between the antibody and the epitope

Question 69

What kind of contact is needed for strong antibody-epitope binding

Answer 69

close contact between epitope and antibody's antigen-binding site

Question 70

What happens if there is a poor fit between the antibody and the epitope

Answer 70

weak or no binding

Question 71

What types of interactions help stabilize antibody-epitope binding?

Answer 71

Hydrogen bonding, ionic bonds, and hydrophobic interactions

Question 72

In serum, IgA is secreted as ..... but in the bodily fluids, IgA is secreted as .....

Answer 72

a monomeric immunoglobulin a dimeric immunoglobulin