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HDM Exam 1 > Adaptive Antigen Recognition in the Immune System > Flashcards

Adaptive Antigen Recognition in the Immune System Flashcards

1
Q

B cell activation overview

A

No need for APC to be activated.
Ags from B cells can be soluble or cell-associated.
Activated B cells are transformed to plasma cells or memory cells.

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2
Q

Plasma cells are found in:

A

Lymphoid organs

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3
Q

T cell activation overview

A

T cells require MHC.

T cells become activated when TCR recognizes Ag presented by APC on MHC.

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4
Q

Signaling structures in BCRs (2)

A

alpha and beta subunits

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5
Q

Signaling in TCRs (2)

A

CD3 and zeta subunit.

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6
Q

Most Abs are found in the ______ in electrophoresis

A

The third slowest migrating group of globulins. (alpha, beta, gamma). Called y-globulins.

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7
Q

Abs have how many polypeptide chains? How are they bound?

A
  1. Two heavy and two light.

Bound by disulfide bridges and noncovalent interactions.

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8
Q

What enzyme cleaves IgG?

A

Papain

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9
Q

How does pepsin cleave Ig?

A

Leaves Fabs attached but lyses the Fc region.

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10
Q

How are the types of Abs determined? (i.e. IgM, IgG, IgA. etc).

A

based on the different H chains.

Referred to as m, d, g, e, a.

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11
Q

Types of L chains (2):

A

k and lambda.

Each weigh 23 kDa.

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12
Q

5 Ig classes:

A 
IgG
IgD
IgE
IgA
IgM
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13
Q

The higher the binding constant:

A

The less likely the Ab is to dissociate from the Ag.

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14
Q

Affinity of primary response vs memory response:

A

Primary response is much lower than memeory response.

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15
Q

Valence of an Ab

A

The maximum number of antigenic determinants with which it can react.
Ex: IgG has 2 Fab regions therefore it can bind 2 Ags = valence of 2.

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16
Q

What is avidity? And what is it dependent on?

A

The measure of the overall strength of the Ab-Ag complex.
It is dependent on affinity of the Ab for the Ag.
Valence of both Ag and Ab.

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17
Q

HAT medium includes (3)

A

Hypoxanthine
Aminopterin
Thymidine

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18
Q

How are myeloma cells that did not hybridize killed in the assay?

A

They lack HGPRT gene are cannot perform purine salvage. This causes only hybrid cells to survive in the HAT medium.

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19
Q

Structure of the TCR

A

Includes alpha and beta TCR noncovalently linked to CD3 and zeta proteins.

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20
Q

CD4 has (3):

A

4 extracellular Ig-like domains
Hydrophobic transmembrane region
Highly basic cytoplasmic tail 38 AA long.

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21
Q

CD2 is composed of 2 related chains called:

A

CD8a and CD8b

22
Q

CDa and CDb have (3):

A

Single Ig-like domain
Hydrophobic transmembrane region.
Highly basic cytoplasmic tail 25 AA long.

23
Q

CD8 interacts with what on the MHC I?

A

B2 microglobulin

24
Q

Antigen binding occurs much faster in:

A

Ig than TCR

25
Q

Steps in maturation of Lymphocytes (4)

A
  1. Commitment of hepatopoietic progenitors to the B or T cell lineage.
  2. Proliferation of the progenitors.
  3. Rearrangement and expression of the Ag receptor.
  4. Selection events to preserve and expand cells that express useful receptors.
26
Q

BCR genes
Ig H chain locus is on:
Ig k chain locus is on:
Ig y chain locus is on:

A

Chromosome 14
Chromosome 2
Chromosome 22

27
Q

TCR genes
TCR beta chain locus is on:
TCR alpha chain locus is on:

A

Chromosome 7

Chromosome 14

28
Q

Allelic exclusion in Abs

A

Only 1 of the L chain and H chain alleles is expressed in a single B cell or T cell (either maternal or paternal).
Bceuase there are so many B/T cells, there is essentially an equal expression from maternal and paternal allotypes.

29
Q

Rag1 and Rag2 function

A

Genes that code for recombination enzymes that act on DNA/RNA to increase diversity of the Ag receptor.
Restricted to B and T cells only during development.

30
Q

Gene segments for the H chain (4):

A 
V-variable
D-diversity
J-joining
C-constant
Each B cell generates its own V-D-J sequence making it unique.
31
Q

How is BCR diversity achieved?

H chain

A

D and J chosen first
V chosen second
C chosen last
There is a test to determine “productive rearrangement”.

32
Q

Junctional diversity does what?

A

Further increases the variety of Ags a TCR or BCR can recognize.

33
Q

Junction diversity mechanism

A

RAG cleaves hairpin loop and adds new N and P nucleotides to increase diversity.

34
Q

Checkpoint #1 of lymphocyte development:

Checkpoint #2 of lymphocyte development:

A

1: After the production of the first polypeptide chain of the 2 chain Ag receptor.
2: Occurs after production of second polypeptide chain.
Both checkpoints ensure that the lymphocyte has complete successful rearrangement.

35
Q

Pre-BCRs contain (1):

A

Ig m heavy chain and surrogate light chain.

36
Q

Pre-TCRs contain (1):

A

TCR beta chain

37
Q

In-frame rearrangements cause:

A

The cell to continue to develop.

30%

38
Q

Out-of-frame rearrangements cause:

A

Pre-Ags not to be expressed and cells undergo apoptosis.

39
Q

Positive selection

A

B and T cells with functional pre-Ag receptors proceed to express genes encoding the second chain of the BCR or TCR.
These cells will reocgnize MHC molecules but not themselves.

40
Q

Negative selection

A

Eliminates harmful T and B cells whose Ag receptors bind to Ags present in bone marrow or thymus.
Harmful T cells undergo apoptosis, but harmful B cells undergo a seoncd attempt in rearrangement of Ig gene.

41
Q

Receptor editing

A

When B cells get another chance to rearrange their Ig gene. If editing fails, B cells die.

42
Q

B cells developing from the fetal live-derived stem cells give rise to:

A

B-1 lineage

43
Q

B cells that arise from bone marrow precursors after birth give rise to:

A

B-2 lineage

44
Q

B-1 cells overview

A

Develop from fetal liver-derived HSCs.
Limited BCR diversity as TdT is not expressed in liver.
Spontaneously secrete IgM. They also secrete the most IgM in early phases of infection.

45
Q

B-2 cells overview

A

Develop from bone marrow.
Relocate to the spleen.
Immature B-2 B cells diferentiate into MZ B-2 cells or FO B-2 cells.

46
Q

FO B-2 cells are:

A

Recirculating lymphocytes. Only FO B-2 cells are dependent upon T cell activation and develop into long-lived plasma and memory cells.

47
Q

MZ B-2 cells are:

A

Abundant in spleen and in the LNs.
Self renewing.
Function independent of T cell help.

48
Q

Negative selection of T cells occurs in:

A

Thymic medulla

49
Q

Positive selection of T cells occurs in:

A

Thymic cortex.

50
Q

What gene is missing in the light chain biosynthesis?

A

D

51
Q

tdT function

A

To add N nucleotides in junctional diversity.

HDM Exam 1 (8 decks)

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