T cell recognition Flashcards

1
Q

TCR

A

T cell receptor

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2
Q

What is a TCR made up of?

A

Alpha-beta heterodimer (small proportion have gamma-delta)

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3
Q

What does a TCR recognise?

A

Antigen complex of antigen peptide fragment with self MHC molecule

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4
Q

Do T cells have CDRs?

A

Yes

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5
Q

How are the alpha and gamma chains organised?

A

Rearrangement of V and J segments + C segment

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6
Q

How are the beta and gamma chains organised?

A

Rearrangement of the V, D, and J segments + C segment

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7
Q

What catalyses the V-J and V-D-J joining?

A

RAG-1/2 recombinase enzyme

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8
Q

What is the major difference between Ig and TCR genes?

A

No somatic mutation in TCR genes

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9
Q

What is the TCR complex made up of?

A

Antigen recognition proteins and invariant signalling proteins

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10
Q

How long is the cytoplasmic tail of TCRs?

A

3 amino acids (too short to signal)

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11
Q

How does TCR signalling occur?

A

Clustering with CD3 and recruiting protein kinases to CD3 cytoplasmic tails

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12
Q

What is CD3 composed of?

A

3 dimers

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13
Q

What are the 2 main groups of T cells

A

CD4+ or CD8+

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14
Q

What do CDs bind to?

A

Conserved regions of MHC molecules

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15
Q

What is the role of MHC molecules?

A

Present antigen to T cell

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16
Q

What does CD4 recognise?

A

MHC class II

17
Q

What does CD8 recognise?

A

MHC class I

18
Q

What is an example of co-stimulatory molecule?

A

B7.1 and B7.2 (CD80 and CD86) on APCs

19
Q

What do co-stimulatory molecules do?

A

Bind to CD28 on T cells (activatory) - induces IL-2 expression

20
Q

What is CTLA-4?

A

Inhibitory receptor for B7 molecules

21
Q

What is the effect of the co-stimulatory signal alone?

A

No effect on T cell (both signals needed - costimulatory and specific signal alone)

22
Q

What happens when T cells are activated?

A

Develop into effector T cells - helper or cytotoxic

23
Q

What do Th cells do?

A

Travel around providing help to B cells and Tc cells. Can activate macrophage or B cell

24
Q

What is the difference in CD4+ T cells?

A

Activated and developed in different cytokine environments

25
Q

What does CTL stand for?

A

Cytotoxic T lymphocytes

26
Q

What controls the strength of the CTL response?

A

Th cells - need exogenous IL-2 to replicate

27
Q

What is needed to generate memory CTLs

A

Th cells

28
Q

What are gamma-delta T cells

A

Mostly CD4-/CD8- or CD8+

29
Q

Where are gamma-delta T cells found and what do they recognise

A

Mainly mucosal tissues. Recognise peptide and non-peptide antigens

30
Q

Do gamma-delta T cells require MHC?

A

No

31
Q

What is the minor (

A

CD1

32
Q

What does CD1 recognise

A

Lipid, glycolipid and other hydrophobic antigens

33
Q

How are CD1 antigens presented?

A

By non-polymorphic CD-1 proteins