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Immuno Block-2 Gems-3
T-cell recpetor
11
Immunology
Graduate
06/10/2011

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Cards

Term
TCR rearrangement
Definition
β-chain rearranged first

Surrogate a chain binds to β-chain

Pre-TCR has β-chain and surrogoate

rearrangement of a chain leads to loss of δ-chain
Term
γδ T cell

Gamma delta
Definition
Appear in fetal thymus.

Do not undergo selection

CD4- & CD8-. Immunosurveilance

Migrate to mucosa and skin, intestines,
lungs

May participate in wound repair.
Term
αβ T cells
Definition
Cd4+: secretion of cytokines
Th1(cell mediated) Th2(Humoral)

Cd8+: cytotoxic(CTL)

NKT cells: Express CD3, recognize
glycolipid and glycopeptides presented
on CD1

Found in lymphatic tissue
Term
T-Cell trafficking and induction of B chain rearrangement
Definition
CD34+ cell migrates from bone marrow to
thymus. (requires c-kit and CD44 on CLP)

c-kit and IL-7R(pro T)
bind SCF and IL-7(Thyroid cell)

Induces TCR gene arrangement
Term
Cortex and medulla TCR development
Definition
Cortex:
TCR and CD3 expression
Induction of expression of CD4 & CD8
Positive selection: MHC recognition ->
CD4 or CD8 commitment

Medulla:
Cell expresses CD4 or CD8

Negative selection: Self-reactive T
cells eliminated
Term
Progression of TCR
Definition
CD34+ CD 44+ lymphoid progenitor

double negative thymocyte

B Chain rearrange Cd4+ Cd8+. Pre-TCR

a chain rearrangement

Positive selection

Single positive thymocyte
Term
Positive Selection TCR
Definition
Positive: αβ T cells by Cortical \
epithelium.

If TCR can bind MHC I or II molecule
then it lives and expresses CD4 or CD*

95% of TCR can not bind MHC and die
CDR1/2 on TCR bind MHC
Term
Negative Selection TCR
Definition
Eliminates self-reactive T cells

High affinity = apoptotic cell death

Weak/moderate cell survival

Treg have moderate self antigen binding
T-regs cause anergy of self-reactive
cells in periphery.
T-reg = CD25+, Foxp3+, CD4+
Term
Central Tolerance
Definition
Result of negative selection of
self-reactive T cells in thymus and of
self-reactive B cells in bone marrow

AIRE - Treg generation.

AIRE is a transcription factor in
medullarly epitheial cells that help
produce self-tissue specific antigens

Induces FoxP3
Term
Peripheral tolerance
Definition
Mechanisms blocking self-reactive T cells that survived negative selection

Peripheral clonal anergy:
Incomplete signal transduction events
Absence of Costimulation
(APC CD80/86 do not bind Cd28 Tcell)

Immune privileged sites
CD95/CD95L binding -> Apoptosis
Term
Co-stimulation. APC - T-cell
Definition
APC Cd80/86 bind to Cd 28 T cell

Signal transduction.
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