Lecture 9: Ag Receptors I Flashcards Preview

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Flashcards in Lecture 9: Ag Receptors I Deck (34):
1

What are the signaling chains of the BCR?

Igalpha and Igbeta

2

What are the signaling chains of the TCR?

CD3 and zeta chain

3

What are the effector functions of the BCR

Fc region of Ab

4

What are teh effector functions of TCRs

No effector function

5

T/F: The structure of the TCR complex is identical for CD4+ and CD8+ T cells

True

6

What is the first costimulatory signal to occur after CR/MHC II binding?

B7-1/2 (CD80/86) is expressed on DC, inducing CD28 expression on T cell

7

If there is TCR/MHC II binding but no costimulation, what happens?

T cell becomes anergic

8

If there is a costimulatory signal alone wth no TCR/MHC II binding, what happens?

No effect on T cell

9

The binding between a TCR and MHC peptide complex is weak. The engagement of its TCRs upregulates chemokine-dependent expression of adhesion molecules on T cell. It holds APC and T cell together for the time required to achieve T cell activation. The clustering of TCRs and adhesion molecules at the point of APC-T cell contact it is called what?

Immunological synapse

10

What cell is LFA-1 found on and what cell is ICAM-1 found on?

LFA-1 is on T cell
ICAM-1 is on APC

11

What is the function of CD3 on T cell?

Signal transduction by TCR

12

What is the function of the zeta chains on T cells?

Signal transduction by TCR complex

13

What is the function of the CD4 chain on T cells?

Adhesion and signal transduction

14

What is the function of CD8 on T cells?

Adhesion and signal transduction

15

What is the function of CD28 on T cells?

Signal transduction (costimulation)

16

What is the function of CTLA-4 on T cells?

Signal transduction -> negative regulation! Stops signal

17

What is the role of LFA-1 on T cells?

Adhesion

18

What is the ligand of LFA-1?

ICAM-1 -> found on APCs

19

What is the ligand for CTLA-4?

B7-1/2 (CD80/86) -> on APC

20

What is the ligand for CD28?

B7-1/2 (CD80/86) -> found on APC

21

What is the ligand for CD8?

Class I MHC -> found on all cell types

22

What is the ligand for CD4?

Class II MHC -> found on APCs

23

What is the ligand for CD3 and zeta chains?

NONE! These are purely for signal transduction

24

What is a coreceptor for BCR and is a specific marker of B cells?

CD19

25

What are the 2 possible mechanisms of B cell activation?

1) Protein Ags activate B cells with assistance of Th cells -> Thymus dependent (TD)
2) Ags of other chemical nature (lipids, carbs, polynucleotides, etc.) activate B cells without the help of T cells -> thymus independent (TI)

26

What is the process of B cell activation by TD Ags?

1) Ag binds BCR
2) Th2 cell delivers the 2nd signal via CD40L and cytokines
3) B cell proliferates and differentiates into plasma cells

27

__________ provides co-stimulatory signal to complete B cell transformation into a plasma cell

CD40/CD40L

28

What is the process of B cell activation by TI Ags?

1) Multiple BCRs bind to a repetitive epitope on bacterium -> causes cross-linking -> cross-linking generates a signal
2) The signal is transducer by Igalpha and Igbeta
3) Enzymes attached to cytoplasmic portion of Igalpha and Igbeta catalyze phosphorylation of signaling molecules

29

Junctional diversity is an important process that contributes to selectivity of Ab to a variety of Ags. Which of the following accurately describe junctional diversity?
A) Enzymatic recombination of the heavy and light chains by RAG enzymes
B) Negative selection of T cells occurring in the thymus
C) Activation via CD80 binding to CD86
D) Cleavage between D and J regions and random addition of base pairs
E) Stimulation of the B cell receptor by CD19

D) Cleavage between D and J regions and random addition of base pairs

30

An Ab made against the Ag tetanus toxoid (TT) reacts with it even when the TT is denatured by disrupting all disulfide bond. Another Ab against TT fails to react when the TT is similarly denatured. What is the most likely explanation for this?

The first Ab is specific for the primary amino acid sequence of TT, whereas the second is specific for conformational determinants

31

The class-specific antigenic determinants (epitopes) of immunoglobulins are associated with which part of the Ab?

H chains

32

The idiotype of an Ab molecule is determined by the amino acid sequence of which regions of the Ab?

Variable regions of the H and L chains

33

Injection into rabbits of a preparation of pooled human IgG could stimulate the production of what 4 anti-Abs?

Anti-gamma heavy chain Ab
Anti-kappa chain Ab
Anti-lambda chain Ab
Anti-Fc Ab

34

A polyclonal antiserum raised against pooled human IgA will react with
A) Human IgM
B) Lambda light chains
C) Human IgG
D) J chain
E) All are correct

E) All are correct