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Immunology Final > Quiz 3 Part 3 > Flashcards

Quiz 3 Part 3 Flashcards

1
Q

What is the 1st antibody to be produced in an antibody response

A

IgM

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2
Q

What are the 2 antibodies on the B cell surface

A

IgM and IgD (BOTH CANT BE ON SAME ANTIBODY —- 1 OR THE OTHER)

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3
Q

What genes are transcribed FIRST

A

C mu and C delta

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4
Q

What is allelic exclusion?

A

allelic exclusion refers to the fact that we only want to make ONE type of antibody at a time, so 1 chromosome is suppressed and one is activated.
1 type of antibody to a single antigen

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5
Q

Where does the uniqueness exist between antibodies?

A

ALWAYS IN VDJ
However, the idea is that we can attach different constant regions to work with different kinds of effector molecules

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6
Q

Explain the process of making IgM and IgD and how they get to the surface of the B cell

A

VDJ has already been joined

transcription occurs through C mu and C delta. Through alternate splicing, either C mu or C delta is chosen to be attached to the VDJ region.

Attached to VDJ and the C mu or C delta is a AAA region. this AAA makes a molecule that has a hydrophobic transmembrane domain to stick into the plasma membrane of the B cell

After the antibody is formed, it has issues getting to the surface of the B cell. Iga and IgB deliver the B cell receptor (the antibody) to the membrane. Iga and IgB have tails that allow for intracellular signaling

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7
Q

When IgM/IgD is being spliced to attach to VDJ, is the DNA being spliced or mRNA?

A

mRNA is being spliced

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8
Q

What happens when B cell receptors bind to an antigen?

A

this binding triggers proliferation and differentiation of B cells into antibody secreting plasma cells

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9
Q

What is somatic hypermutation?

A

somatic hypermutation introduces POINT MUTATIONS (addition/deletion/changing of a single base) throughout rearranged variable regions.

If this mutation increases affinity for the antigen, the B cell is selected to mature into plasma cells that begin secreting antibodies

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10
Q

Somatic hypermutation is dependent on…..

A

AID activity (activation-induced cytidine deaminase)

Activation-induced cytidine deaminase is ONLY produced in proliferating B cells (those that have been activated by antigen)

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11
Q

Due to somatic hypermutation, antibodies of increasingly higher affinity for the antigen are produced. what is the term for this?

A

AFFINITY MATURATION

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12
Q

Explain the difference between the B cell receptor IgM and the secreted IgM

A

the B cell receptor IgM is a monomer while the secreted form is a circular pentamer

the secreted IgM is not very effective. It is a bulky molecule with low-affinity sites. It has a small hinge region, and is so big that it has issues moving around efficiently

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13
Q

Secreted (pentameric) IgM coordinates with….

A

J chain

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14
Q

Is IgM heavily involved in the antibody response?

A

no — it is really only a receptor.
the secreted version is too bulky to be involved

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15
Q

What part of an antibody gives it the ability to interact with different effector molecules?

A

the constant region

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16
Q

What is isotype switching

A

Switching IgM for something more useful

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17
Q

When does isotype switching occur? What is isotype switching dependent on?

A

isotype switching ONLY occurs in B cells in response to an antigen.

like somatic hypermutation, it is also dependent on AID ( activation-induced cytidine deaminase)

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18
Q

In isotype switching, is the variable region being changed?

A

NO—–only the constant region (C region)

19
Q

Isotype switching is regulated by….

A

cytokine signaling.
Cytokines stimulate different transcription factors. They stimulate SPECIFIC transcription

20
Q

VDJ ALWAYS GIVES…..

A

antigen specificity

21
Q

In somatic hypermutation, AID causes the ___ to become ____

A

C’s to become U’s

22
Q

Explain how isotype switching is done

A

CYTOKINES turn promoters in the switch region ON. This causes AID to add in the U’s at the switch regions which causes a break in the DNA. a loop is formed and a circular piece of all the unneeded things breaks off and the new constant region is now attached to VDJ and transcription occurs

23
Q

is isotype switching done on DNA or RNA

A

DNA

24
Q

Is spacing a concern in isotype switching?

A

NO

25
Q

When is spacing a concern? (frameshift mutations)

A

in junctional diversity (RAG complex)
DJ joining

26
Q

What are 3 mechanisms for antibodies to clear pathogens

A

neutralization —- directly inactivate the pathogen or toxin

opsonization — coating with antibody to enhance phagocytosis. (phagocytes express Fc receptors)

complement activation — binding of C1 complement protein

27
Q

can antibodies trigger complement

A

yes —- the binding of C1 complement protein

28
Q

How does opsonization of a pathogen by an antibody help to enhance phagocytosis

A

phagocytes express Fc receptors (Fc = tail region of proteased antibody)

29
Q

Which type of immunoglobulin is best at neutralization and opsonization and is also most plentiful in our serum

A

IgG1,2,3

30
Q

Which immunoglobulin is involved in giving maternal antibodies to the fetus through the placenta

A

IgG1

31
Q

Which immunoglobulins have the ability to activate complement

A

IgG and IgM

32
Q

Are IgM’s mainly found in the blood or tissues?

A

BLOOD — they’re too big to enter tissues

33
Q

What is the function of IgA

A

to keep the commensal bacterial population in check. this is the MOST PRODUCED OF ANY ISOTYPE. predominantly made in MALTS

34
Q

What is the function of IgE

A

to mediate allergic reactions. involved in the recruitment of mast cells, eosinophils and basophils.

35
Q

Cells have a very high affinity for which immunoglobulin receptor?

A

IgE (mediate allergic reactions)

36
Q

What is the function of IgD

A

to protect mucosal surfaces (found in upper airways of the bronchial tract)

37
Q

Which cells have a high affinity IgD receptor

A

basophils

38
Q

What is the most abundant immunoglobulin in internal bodily fluids

A

the 4 subclasses of IgG — 1-4

39
Q

Which immunoglobulin has a high degree of conformational flexibility

A

IgG

40
Q

Explain how IgG has a high degree of conformational flexibility

A

Fab and Fc regions move in a partly independent matter which enhances binding ability

However, the flexible hinge of IgG is also subject to proteolysis

41
Q

Name the 4 things that IgG can do that shows flexibility

A

WAVE – the fab arms
WAG – the Fc tail
ROTATE – the Fab arm
BEND – the Fab elbow

42
Q

Which class of IgG has the largest hinge
which has the second largest

A

IgG3 – largest by far

IgG2– secon largest hinge

43
Q
A

Immunology Final (12 decks)

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