10 T and B cell effectors

Question 1

what expresses MHC 1

Answer 1

nucleated cells (and APC)

Question 2

what expresses MHC 2

Answer 2

APC

Question 3

where are cytosolic pathogens degraded

Answer 3

cytosol

Question 4

what do cytosolic pathogens bind to

Answer 4

MHC 1

Question 5

what are cytosolic pathogens presented to

Answer 5

effector CD8 T cells

Question 6

what is the effect on presenting cytosolic pathogens to cell

Answer 6

cell death

Question 7

where are cross-presentation of exogenous antigens degraded

Answer 7

cytosol (by retrotranslocation)

Question 8

what do cross-presentation of exogenous antigens bind to

Answer 8

MHC 1

Question 9

what are cross-presentation of exogenous antigens presented to

Answer 9

naive CD8 T cells

Question 10

what is the effect when cross-presentation of exogenous antigens are presented to cell

Answer 10

the presenting cell usually a dendritic cell, activates CD8 T cell

Question 11

where are the intravesicular pathogens

Answer 11

endocytic vesicles (low pH)

Question 12

what do the intravesicular pathogens bind to

Answer 12

MHC 2

Question 13

what are the intravesicular pathogens presented to

Answer 13

effector CD4 T cells

Question 14

what is the effect when intravesicular pathogens are presented

Answer 14

activation to kill intravesicular bacteria and parasites

Question 15

where are the extracellular pathogens and toxins degraded in

Answer 15

endocytic vesicles (low pH)

Question 16

what are the peptides that the extracellular pathogens and toxins bind to

Answer 16

MHC 2

Question 17

what are the extracellular pathogens and toxins presented to

Answer 17

effector CD4 T cells

Question 18

what is the effect of extracellular pathogen and toxins when presented to cell

Answer 18

activation of B cells to secrete Ig to eliminate extracellular bacteria/toxins

Question 19

cellular response

Answer 19

Cytotoxic t cell CD8 release perforin – causes target cell to lyse

Question 20

humoral response

Answer 20

Helper CD4 cell

Question 21

types of uptake

Answer 21

cellular and humoral

Question 22

cellular immune response

Answer 22

antigen as intracellular

Question 23

humoral immune response

Answer 23

antigen is extracellular

Question 24

cellular response

Answer 24

Cytotoxic t cell CD8 release perforin – causes target cell to lyse

Question 25

humoral response

Answer 25

Helper CD4 cell

Question 26

types of uptake

Answer 26

cellular and humoral

Question 27

cellular immune response

Answer 27

antigen as intracellular

Question 28

humoral immune response

Answer 28

antigen is extracellular

Question 29

Antigen presenting: Cellular response

Answer 29

``` Partly folded MHC class 1 in ribosome binds a proteins. Cytosolic proteins and defective ribosomal products degraded are taken to ER Peptide bins MHC class 1, completes folding, MHC released from TAP to go to cell membrane ```

Question 30

Antigen presenting: Humoral response

Answer 30

1. invariant chain (li) forms complex with MHC class 2 molecule, blocking peptides binding and misfolded proteins 2. li is cleaved in an acidified endosome, leaving short peptide fragment, CLIP, still bound to the MHC 2 3. endocytosed antigens degraded to peptides in endosomes, CLIP peptide blocks binding of peptides to MHC 2 4. HLA-DM binds to MHC 2 releasing CLIP, allowing other peptides to bind. MHC 2 travels to cell surface

Question 31

Activation phase (MHC 2) Immune system cells - Bacterium

Answer 31

1. Bacterium infects macrophage and enters vesicle, producing peptide fragments 2. Bacterial fragments bound by MHC class 2 in vesicles 3. Bound peptides transported by MHC class 2 to the cell surface

Question 32

Activation phase (MHC 2) Immune system cells - antigen

Answer 32

1. Antigen bound by B-cell surface receptor 2. Antigen internalized and degraded to peptide fragments 3. Fragments bind to MHC class 2 and transported to cell surface

Question 33

how are macrophages activated

Answer 33

TH1 cell recognises complex of bacterial peptide with MHC class 2 and activates macrophages

Question 34

how are B cells activated

Answer 34

``` Helper T cell recognises complex of antigenic peptide with MHC class 2 and activates B cell CD4 T cells MHC 2 ```

Question 35

Activation phase (MHC 1) – All cells

Answer 35

Virus infects cell Viral proteins synthesised in cytosol Peptide fragments of viral proteins bound by MHC class 1 in ER Bound peptides transported by MHC class 1 to cell surface

Question 36

Effector phase (MHC 1)

Answer 36

``` Cytotoxic T cell recognises complex of viral peptide with MHC class 1 and kills infected cell CD8 T cells MHC 1 ```

Question 37

positive selection

Answer 37

not viable if do not bind to a specific peptide

Question 38

negative selection

Answer 38

bind too tightly so die)

Question 39

Positive negative selection

Answer 39

Not all combinations of MHC loaded peptides and T cell are possible Selection for affinity and self must take place

Question 40

what occurs in positive and negative selection

Answer 40

1. T-cell precursor rearranges its T-cell receptor genes in thymus 2. Immature T cells that recognise self MHC receive signals for survival. Those that interact with self-antigen are removed 3. mature T cells encounter foreign antigens in peripheral lymphoid organs and are activated 4. activated T cells proliferate and eliminate infection