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Molecular Immunology > Lecture 9: Antibody Responses and Biology of T Lymphocytes > Flashcards

Lecture 9: Antibody Responses and Biology of T Lymphocytes Flashcards

1
Q

True or False: IgA can be passively acquired via breastmilk

A

True

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2
Q

True or False: At 6 months of age, newborns have compromised humoral immunity

A

True

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3
Q

Compare the maternally derived antibody vs. the infant derived antibodies?

A

Maternally derived = IgG
Infant derived = IgG, IgA, and IgM

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4
Q

If a baby appears sick after and you want to investigate the case, which antibodies should you inquire into?

A

IgM and IgA

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5
Q

In utero synthesis of antibody indicates ___ exposure to infectious agent/antigen

A

in utero

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6
Q

How can T-independent antigens become T-dependent?

A

If they are conjugated to T-dependent antigen, as in the case of the H. influenzae vaccine

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7
Q

True or False: In T-independent antigens, there is affinity maturation and memory response

A

False - there is neither affinity maturation or memory response in T-independent antigens

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8
Q

What is the ONLY class of Ab made in T-independent antigens?

A

IgM

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9
Q

True or False: there are cytokines present in T-independent antigens

A

False - no T cells means no cytokines

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10
Q

How does activation occur in T-independent antigens?

A

Cross-linking of Ig receptors leads to intracellular signaling and activation (antibody secretion)

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11
Q

True or False: Both T-dependent and T-independent antigens require processing

A

False - only T-dependent antigens require processing (exogenous)

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12
Q

True or False: Carbohydrates can be put into HLA II molecules

A

False - they cannot since they are carbs and not peptides

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13
Q

T-dependent antigens are typically ___ while T-independent antigens are typically ___

A

T-dependent = proteins
T-independent = carbohydrates

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14
Q

True or False: As the immune system/response develops, the overall affinity for antibodies found in a person will increase as well

A

True

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15
Q

True or False: At the end of an immune response, antibody molecules will have a lower affinity compared to initial stages

A

False - at the end of an immune response, antibody molecules will have a HIGHER affinity compared to initial stages

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16
Q

As the immune response proceeds and antigen disappears, there is a selection for best binding antibody, which is known as: ____

A

Affinity maturation (T-dependent only)

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17
Q

True or False: Antigen specificity never changes in a mature B cells

A

True

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18
Q

Where does processing of first and second dose of antigen occur?

A

Secondary lymph organs (spleen and lymph nodes)

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19
Q

How long before Ab is detected in response to first dose of Ag in T-dependent interactions? second dose of Ag?

A

First dose = 7 to 10 days
Second dose = 3 days

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20
Q

What is the predominant Ab isotype in secondary response?

A

IgG

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21
Q

What is the first isotope produced in response to first dose of Ag? (In other words: during a T-dependent response, what molecule is always secreted first)

A

IgM

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22
Q

True or False: During the second antigen dose, more IgG is made and it “sticks around longer than IgM

A

True - IgG has longer half life

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23
Q

Elevated IgG that you see during end of first antigen dose response is the result of what?

A

IgG becoming plasma cells

24
Q

True or False: IgG can convert to plasma or memory cells

A

TRUE

25
Q

What would a clinician see with a second antigen dose? What sort of response is this?

A

Elevated IgG and total
- Memory Response

26
Q

What is the net result of primary antibody response to T-dependent antigen?

A

Increase number of memory cell clones, which respond more rapidly to second challenge with antigen

27
Q

True or False: During T-dependent antibody responses, Th2 cells promote ____ while Th1 cells promote ___

A

Th2: IgG, IgA, and IgE
Th1: Specific switch to IgG3

28
Q

In T-dependent response, interaction with T cell and its cytokines induces ____

A

isotype switch

29
Q

True or False: Cells in T-dependent antibody responses will undergo proliferation, expansion, and differentiation (plasma or memory cell)

A

True

30
Q

True or False: Activate T Helper cells give co-stimulatory signals through both cell:cell interactions and cytokines

A

True

31
Q

How does the T-dependent response work?

A

1) APC takes in bacteria (exogenous pathway)
2) Puts peptide in HLA/MHC II context
3) APC activates T Helper Cell

At the same time: there is a B cell with antibody on the surface, specific for SAME antigen
1) B cell binds to antigen and takes it in (exogenous pathway)
2) Same peptide presented HLA/MHC II on B cell

Ultimately, the T helper cell and B cell find each other

32
Q

True or False: T-dependent antibody antigens are proteins and require processing

A

True

33
Q

True or False: Clonal anergy is associated with soluble molecules while clonal deletion is associated with apoptosis

A

True

34
Q

If circulating, self-reactive cells come into contact with self antigens WITHOUT co-stimulation, what occurs?

A

Anergy
- Peripheral B Cell Tolerance

35
Q

What happens once mature B cell leaves bone marrow? Possible outcomes?

A

Looks for antigens in circulation
1) Finds Ag = B cell activated
2) Does not find Ag = die (death by neglect)

36
Q

What are the two major checkpoints during B cell development?

A

Checkpoint 1: Pre-B Cell (does the heavy chain work)

Checkpoint 2: Immature B cell (is Ig on surface of self reactive)

37
Q

During immature B cell stage, if cell encounters antigens that it CANNOT interact with ___ occurs.

If cell encounters antigens that it CAN interact with ____ occurs.

A

CANNOT interact = Clonal anergy
CAN interact = Clonal deletion (apoptosis)

38
Q

When does antigen specificity occur in B cell development?

A
  • When genes for variable region of molecule are rearranged
39
Q

True or False: Specificity remains same throughout one’s life

A

True

40
Q

Allelic exclusion is associated with which stage of antigen-independent differentiation?

A

Pre B Cell

41
Q

What distinguishes Pre-B cell?

A

1) Cytoplasmic mu
2) Fully re-arranged Ig heavy chain

42
Q

Net result of primary T-dependent antibody response?

A

Increase number of clones that will be pre-committed to responding to antigen that induces response

43
Q

If self-reactive B cell escapes central tolerance, how is it maintained?

A

Peripheral B Cell Tolerance

44
Q

Where does Central B Cell Tolerance occur? What stage?

A

Bone marrow
- Immature B cell stage

45
Q

What happens as a result of Central B Cell tolerance?

A
  • Multivalent self molecule = clonal deletion (apoptosis)
  • Soluble self molecule = clonal anergy (non-responsive)
46
Q

True or False: Soluble self molecules/anergy is associated with WEAK signals whereas clonal deletion/apoptosis is associated with STRONG signals

A

True

47
Q

At what stage of antigen-independent B cell differentiation does selection for self-reactivity occur?

A

Immature B cell stage

48
Q

What theory explains how selection occurs? What does the theory state?

A

Ag Clonal Selection Theory
1) Selection is by the antigen
2) Once B cell is activated, it will undergo proliferation and differentiation (plasma or memory cell)
3) Self reactive B cells must be controlled

49
Q

Net effect of clonal anergy and clonal deletion?

A

Get rid of cells prone to responding to self antigens

50
Q

Where does antigen dependent differentiation occur?

Where does antigen independent differentiation occur?

A

Antigen dependent = 2 lymphoid tissues (Spleen)
Antigen independent = bone marrow

51
Q

Where are mature B cells found?

A

Spleen, Lymph, Peripheral blood

52
Q

What two molecules are found on surface of mature B cell? Do they have same specificities?

A

sIgM and sIgD (due to differential splicing of RNA)
- Same specificity, despite different Fc portions

53
Q

Two possible fates of Immature B cell?

A

1) Clonal Anergy = B cell becomes tolerant
2) Clonal Deletion = B cell undergoes apoptosis

54
Q

At what stage do immunoglobulins genes for variable heavy region undergo rearrangement?

A

Pro B cell stage

55
Q

What defines a Pre-B cell?

What defines an Immature B cell?

A

Pre-B cell
- Variable heavy chain is rearranged; mu heavy chains

Immature
- sIgM (u heavy chain + light chain)

56
Q

At what stage of antigen-independent differentiation of B cells is the rearranged heavy chain tested (checkpoint 1)

A

Pre B cell stage (if it works: no further rearrangement is needed)

57
Q

What can one conclude if surrogate light chain and heavy chain get to surface of cells during Pre-B cell stage?

A

1) Heavy chain is functional
2) Allelic expression can be achieved

Molecular Immunology (27 decks)

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