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Block 6 Week 1 > Hudig: B Cells and Humoral Immunity > Flashcards

Hudig: B Cells and Humoral Immunity Flashcards

1
Q

This type of immunity is transferred by serum containing antibodies or by antibodies alone

A

humoral immunity

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2
Q

Humoral immunity is transferred by serum containing (blank) or by (blank) alone

A

antibodies

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3
Q

This type of immunity is transferred only by cells (usu only performed in mice or rates)

A

cellular immunity

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4
Q

When antibodies (humoral immunity) are transferred within a species, what happens? What if they are transferred across species?

A

Within a species, they are accepted as self and effective. Cross-species Ab’s last 5-7days

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5
Q

What happens when you attempt to transfer T-cell mediated immunity, like CD8 anti-viral CTLs to an outbred animal in the same species?

A

T cells are rejected because MHC I and II antigens will be mismatched and different, and will lead to the killing of the transferred cells

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6
Q

What are these considered:

Proteins >25micrograms
Killed pathogens
Live attenuated viruses
Conjugate and DNA vaccines

A

immunogens

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7
Q

What is the job of an adjuvant?

A

An adjuvant is something that is added to a vaccine to improve the immunization, but it is not immunogenic itself. It helps activate macrophages to produce IL1 and TNFalpha to activate T and B cells. It can also be used to keep immunogens localized or to keep them around for longer (ex: oils)

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8
Q

The route of antibody administration determines which class of antibody will be produced. If given intramuscularly, which will be produced? If given orally, which will be produced?

A

Intramuscular: IgG Ab

Oral or nasal: IgA antibody

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9
Q

Is IV a good route for antibody administration?

A

No

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10
Q

What is the purpose of repeated exposure to a vaccine?

A

increases the QUANITY and AFFINITY of IgG and IgA

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11
Q

What is the difference between affinity and avidity?

A

Affinity: measure of binding strength of a single Fab antigen-binding site for its single antigen epitope

Avidity: measure of the total combined binding strength of the entire immunoglobulin molecule for a complex antigen

(Avidity is multiple interactions, like Velcro. Some Igs are multimers, like IgM with 10 binding sites. If it binds to an antigenic surface w many repeats, it binds w high avidity.)

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12
Q

When does antibody affinity matter? Give 3 examples of toxins which require high antibody affinity.

A

Affinity can really matter if a toxin is really affective. In this case, you need an Ab that can compete.

Ex: anti-botulin toxin, ebola virus, tetanus toxin

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13
Q

What are the 5 classes of immunoglobulin? Which have subclasses?

A 
IgA *IgA1, IgA2
IgD
IgE
IgG *IgG1, IgG2, IgG3, IgG4
IgM
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14
Q

IgM

How many units are there of the basic Ig unit?
What holds the repeats together?
What is the relative molecular weight?
How many antigen binding sites?

A

5 units; disulfide bonds and the J chain which is INSIDE the polymer; >750kD; 10 antigen binding sites

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15
Q

Which antibody is the first to be made in immune responses right after antigen is introduced?

A

IgM

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16
Q

Does IgM has high or low affinity for antigens?

A

low affinity, but high avidity

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17
Q

What is the serum concentration of IgM?

What is the serum half life?

A

~1.2mg/ml

~5 days

18
Q

Where is IgM also found in addition to the serum?

A

secretions

19
Q

What is the function of IgM?

A

it “fixes” complement **a single IgM antibody can start the whole cascade of complement killing

20
Q

What is the structure of IgG? What is the molecular weight? What are the differences among the 4 classes of IgG? How many antigen binding sites?

A

it is a monomer; ~150kD; different classes differ in their hinge region and in the sequences of the constant regions of the heavy chain; 2 antigen binding sites

21
Q

When is IgG made?
What is its serum half life?
How long does it last?

A

it is made second after IgM; 1/2 life of IgG1, 2, and 4 is ~22 days, while the 1/2 life IgG3 is ~7 days; it lasts for a lifetime

22
Q

Does IgG have high or low affinity for antigen?

A

high affinity for antigen

23
Q

3 functions of IgG?

A
  1. IgG1 and IgG3 fix complement when there are at least 2 IgGs close together on a bacterium
  2. IgG1 and IgG3 also support antibody-dependent cell-mediated cytotoxicity
  3. IgG crosses the placenta to provide neonatal immunity
24
Q

Which immunoglobulin crosses the placenta to confer passive immunity to a neonate?

A

IgG

**around 6mo, the antibody has been eaten up so the baby may start to develop infections or a cold

25
Q

What is the structure of IgA? What is its molecular weight? Where is its J chain? How many antigen binding sites?

A

dimer OR trimer; ~150kD; J chain holds it together; 4 or 6 antigen binding sites

26
Q

What are the 2 subclasses of IgA?

A

IgA1 and IgA2

27
Q

Where is IgA found?

A

plasma and in SECRETIONS: breast milk, gut, tears, saliva, vagina

28
Q

Does IgA from mother’s breast milk enter the baby’s circulation?

A

No, stays in the baby’s gut

29
Q

What is the serum 1/2 life of IgA?

A

6 days or so

30
Q

What is the function of IgA?

A

to block pathogens at mucosal sites, cause adhesion of pathogens, and their attachment to the gut wall

31
Q

How is IgA transported through epithelial cells into mucosal secretions?

A

via secretory component - this is the transport receptor for IgA

**IgM in secretions also has secretory component

32
Q

What is the structure of IgD? Molecular weight? Where is it found? How many antigen binding sites?

A

monomer; ~180kD; found on virgin B cells; 2 antigen binding sites

33
Q

What is the structure of IgE? Molecular weight? Where is it found? Serum half life?

A

Monomer; ~180kD; found in plasma and/or bound to mast cells and basophils; 1/2 life of 1-2 days

34
Q

What is unique about the concentration of IgE?

A

very low

35
Q

What is unique about the activation of IgE?

A

You need multivalent antigens to cross link on at least 2 IgE antibodies to cause mast cells and basophils to release their granules and induce and allergic response

36
Q

What test can be used in vivo to diagnose IgE allergic responses? What test can be used in vitro?

A

skin prick test or intradermal; test serum for IgE using something like ImmunoCAP

37
Q

What are the 5 mechanisms of protection by antibodies?

A
  1. neutralize toxins by blocking the binding chain of the toxin
  2. block adhesion to prevent bacterial and viral entry into cells and to stop bacteria from crossing into the body from the gut
  3. Initiate complement
  4. Support neutrophils in the killing of yeast and bacteria
  5. ADCC of infected host cells and parasites
38
Q

How do antibodies block viruses from entering cells?

A

they can block the binding of the virus to its receptor and also block the fusion so the virus can not be endocytosed into the cell

39
Q

Why is it good that antibodies initiate complement?

A

because this allows them to opsonize bacteria and yeast and potentially kill them

40
Q

What is antibody dependent cell-mediated cytotoxicity? (ADCC)

A

So you have a target cell expressing antigens. IgG1 and IgG3 antibodies specific to the antigens on the target cell bind to the target cell. Te Fc region of the antibodies binds to an NK cell. The NK cell does the killing, but the antibodies recognize the antigen, and bind both to the target cell and to the NK cell to bring them close together and to induce killing.

41
Q

What marker is used to determine if death of the target cell has occurred in antibody-dependent cell-mediated cytotoxicity?

A

Cr51

Block 6 Week 1 (13 decks)

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