L8 T Cell Immunity

Question 1

What are viruses?

Answer 1

Intracellular parasites

Question 2

Examples of non-enveloped (naked) viruses:

Answer 2

Norovirus, Poliovirus

Question 3

Examples of enveloped viruses:

Answer 3

Influenza virus, HIV (human immunodeficiency virus)

Question 4

How do naked viruses work?

Answer 4

They infect the cell and cause cell lysis. The progeny viruses then escape

Question 5

How do enveloped viruses work?

Answer 5

During infection, viral envelope proteins insert into the cell membrane of an infected cell. The progeny viruses then ‘bud off’

Question 6

How can virus envelope proteins on the surface of an infected cell be targeted?

Answer 6

1. Antibody/complement: lysis & phagocytosis

2. ADCC, leading to apoptosis

Question 7

T cells only recognise short peptides (result from protein degradation in proteasome) when…

Answer 7

they are bound to MHC molecules on either APCs or infected cells

Question 8

What is the main role of T cells?

Answer 8

eliminate microbes that survive inside cells

Question 9

Do T cells recognise cell-associated or ‘free’ antigens?

Answer 9

cell-associated antigens (e.g. viruses and M. tuberculosis)

Question 10

TCR α and β chains have a net __ charge

Answer 10

positive

Question 11

How many other proteins is TCR non-covalently associated with?

Answer 11

5 other proteins (CD3 complex)

Question 12

Transmembrane portions of ε 𝛾 δ ζ contain __ charged __ __ residues

Answer 12

NEGATIVELY charged ASPARTIC ACID residues

Question 13

What makes up the ‘tri-molecular complex’

Answer 13

TCR/Antigen/MHC

Question 14

What happens during thymic education?

Answer 14

Any T cells that could potentially attack our own ‘self-antigens’ on/in cells/tissues are eliminated

Question 15

What cells are involved in the process of thymic education?

Answer 15

Interdigitating dendritic cells, cortical epithelial cells, macrophages

Question 16

Thymocytes are derived from…

Answer 16

lymphoid stem cells

Question 17

Positive selection of T cells for dual recognition of:

Answer 17

1. Functional TCR on T cell surface

2. Recognises MHC molecules on APC surface

Question 18

What does negative selection involve?

Answer 18

Deletion of ‘self-reacting’ T cells. Ff TCR recognises self-antigens, it is killed by APCs → apoptosis

Question 19

Where does T cell education take place?

Answer 19

Thymus

Question 20

Which chemokine attracts progenitors to the thymus?

Answer 20

CCL25

Question 21

Which cytokine supports thymocyte proliferation?

Answer 21

IL-7

Question 22

What do MHC and HLA stand for?

Answer 22

Major Histocompatibility Complex

Human Leukocyte Antigens

Question 23

What genes are responsible for tissue/organ rejection?

Answer 23

MHC genes

Question 24

Random recombination of V & J genes occurs in TCRs. Is this also seen in MHC genes?

Answer 24

No

Question 25

The MHC genes are inherited as...

Answer 25

distinct genetic loci (you inherit one MHC copy from your mother and one from your father)

Question 26

What are the 3 MHC Class 1 genes?

Answer 26

HLA-A, HLA-B, HLA-C (a single gene for each, producing a single α chain protein)

Question 27

What are the 3 MHC Class 2 genes?

Answer 27

HLA-DP, HLA-DQ, HLA-DR (2 genes for each, producing an α chain & a β chain)

Question 28

Every individual has their own set of MHC genes: True or False

Answer 28

True

Question 29

How are MHC proteins expressed?

Answer 29

Co-dominantly expressed - 2 of each of the 6 types are expressed (HLA-A, HLA-B, HLA-C, HLA-DP, HLA-DQ, HLA-DR)

Question 30

Are genes within the MHC chromosomal locus tightly linked?

Answer 30

Yes - this means that they're inherited as a unit called a haplotype. We inherit one MHC haplotype from each parent (people are usually heterozygous)

Question 31

Where are MHC I proteins expressed?

Answer 31

On the surface of all nucleated cells (they present self-antigens & virus antigens to CTLs)

Question 32

Where are MHC II proteins mainly found?

Answer 32

On the surface of APCs (present foreign antigens to Th cells)

Question 33

Does the MHC/peptide complex have a short or long half-life?

Answer 33

Long

Question 34

What is the significance of each MHC having different amino acid residues in its cleft?

Answer 34

Different MHC alleles favour binding of different peptides

Question 35

Proteins degraded in __ normally provide peptides for MHC Class I

Answer 35

proteosomes

Question 36

Proteins degraded in __ provide peptides for MHC Class II

Answer 36

endo-lysosomes

Question 37

To which cells can dendritic cells cross-present?

Answer 37

CD4+ Th cells, CD8+ CTLs