T Cells: TCR and Thymic Differentiation (Exam 2)

Both TCRs and BCRs are ______ specific and ______ distributed.

antigen, clonally

Both TCRs and BCRs are generated via ______ gene rearrangement.

V(D)J

TCRs can be either ______ or ______.

αβ (more common), ɣ𝛿 (few)

TCR subunits

One alpha, one beta (or one gamma, one delta)

TCRs have ______ chain(s) and ______ antigen binding site(s).

2, 1

TCRs predominantly recognize ______ antigens.

protein/peptide

The protein/peptide that TCRs recognize must be bound to ______.

MHC

TCRs can only interact with other ______.

cells

TCRs ______(are/are not) secreted on activation.

are not

Does TCR structure change upon response to antigen?

No

BCRs have ______ chain(s).

4

BCRs can recognize ...

Carbohydrate, DNA, lipid, protein

BCRs can recognize ______ antigen.

free

BCRs can deal with any antigen in ______.

body fluids

BCRs ______ (are/are not) secreted upon activation.

are

BCRs can undergo ______ and ______, while TCRs cannot.

somatic hypermutation, class switch recombinase

______ co-receptor is found exclusively on the surface of T cells.

CD3

CD3 functions in ______.

signal transduction

What are the other T cell co-receptors?

CD4 or CD8

CD4 and CD8 only bind ______.

MHCII, MHCI (repsectively)

CD4/8 function as ______ molecules and are essential in ______.

adhesion, signal transduction

______ (virus) can bind to CD4.

HIV-1

TCR and co-receptors

ɣ𝛿 T cells are found at ______ and in ______.

mucosal epithelia, circulation (small numbers)

ɣ𝛿 T cells respond ______.

rapidly

ɣ𝛿 T cells secrete ______.

cytokines

ɣ𝛿 T cells do not bind to ______.

MHC

ɣ𝛿 T cells are ______-like T cells.

innate

ɣ𝛿 T cells also possess ______ on the surface.

CD3

What rearrangement comes first in TCR recombination? (beta/delta or alpha/gamma)

beta and delta (these act as the heavy chains)

Once one of the "heavy" TCR chains is chosen, its corresponding ______ chain will be chosen.

"light" (alpha or gamma)

If beta is chosen first, ______ cannot be chosen second (allelic exclusion).

gamma

If delta is chosen first, ______ cannot be chosen second (allelic exclusion).

alpha

TCR diversity is generated by ...

- V(D)J gene rearrangements

- Random combination of chains

- Improper joining during recombination

TCR diversity does not occur through ______.

somatic hypermutation

The ______ is the primary site for T cell differentiation.

thymus

T cell differentiation ______ after puberty.

declines

What two things occur in the thymus in regard to TCR formation?

Positive and negative selection

Prior to positive selection, T cells are ______.

double positive (CD4+/CD8+)

Once the CD4+/CD8+ T cell receptor interacts with MHC, ______ occurs.

positive selection

This interaction determines the ______ that the T cell will commit to.

lineage (CD4 or CD8)

If no CD4+/CD8+:MHC interaction occurs, the T cell will ______.

die (most cells)

Positive selection selects for the T cells that can recognize ______.

self (MHC restricted)

Positive selection occurs in the ______.

thymic cortex

Prior to negative selection, T cells are ______.

single positive (CD4+ OR CD8+)

When these CD4+ or CD8+ T cells interact with their corresponding MHC, the ______ of the interaction is assessed.

affinity

If there is a high affinity, T cells will undergo negative selection and ______.

die

If there is low/intermediate affinity interaction, the cells will ______.

survive

Negative selection produces T cells that are ______ of self.

tolerant

Negative selection occurs in the ______.

thymic medulla

Mature T cells enter ______ to respond to MHC:antigen.

peripheral lymphoid organs

TCR structures