antigen recognition by T lymphocytes

Question 1

do t cells under go somatic hypermutation? and why would you want it to happen or not.

Answer 1

No, you do not want t-cells to incorporate random mutations into their ability to recognize self

Question 2

qualities of T cells compared to B cells

Answer 2

• have different MHCs and only have peptides
• has surface expression of receptor which doubles as effector molecule
• no somatic hypermutation
• no constant region switching
• interacts with other cells
• clonal populations

Question 3

Do T cells have heavy and light chains?

Answer 3

No, they have alpha and beta chains

Question 4

structure of a T cell

Answer 4

1 alpha chain, 1 beta chain, 6 hypervariable loops (3 on each arm), single binding site with multipoint attachment

Question 5

is T cell receptor diversity is generated by gene rearrangement

Answer 5

Yes

Question 6

where does TCR gene recombination take place

Answer 6

in the thymus

Question 7

how to fix severe combined immunodeficiency and Omenn syndrome

Answer 7

bone marrow transplant

Question 8

what genes are key elements in the origin of adaptive immunity

Answer 8

RAG genes

Question 9

what chromosome is the RAG genes on

Answer 9

11

Question 10

does expression of the t cell receptor on the cell surface requires association with additional protein

Answer 10

yes, it is required for transport from the ER, signal transduction

Question 11

what does the absence of epsilon and delta lead to

Answer 11

immunodeficiency

Question 12

how specific do the alpha and beta t cells need peptides to be given to them

Answer 12

need to be given directly

Question 13

how specific do the gamma and delta t cells need peptides to be given to them

Answer 13

they do not care how the peptide is given to them

Question 14

what percent of T cells are in circulation

Answer 14

1-5%

Question 15

what causes T cell receptors to recognize MHC molecules

Answer 15

peptide antigens

Question 16

MHC class 1 structure

Answer 16

has a beta 2 macroglobulin attached to the rest of the protein structure

Question 17

MHC class 2 structure

Answer 17

symmetrical structure

Question 18

what do MHC class 1 present to

Answer 18

CD8+ cells (killer t cells)

Question 19

what do MHC class 2 molecules present to

Answer 19

CD4+ (helper t cells)

Question 20

which cells are exploited by HIV

Answer 20

CD4 and CD8 glycoproteins

Question 21

what do CD8 t cells do when recognizing viral antigens

Answer 21

find the MHC class 1 presenting the viral protein, and kill the infected epithelial cell

Question 22

what do CD4 t cells do when recognizing viral antigens

Answer 22

when the MHC class 2 presents the viral protein it binds to it, releases cytokines in order to activate the macrophage which will then kill the cell.

Question 23

which MHC cell has a dual chain binding groove

Answer 23

MHC 2

Question 24

which cellular compartment does MHC class 1 function

Answer 24

intracellular in the cytosol and ER

Question 25

which cellular compartment does MHC class 2 function

Answer 25

extracellular, in the endosomes and lysosomes

Question 26

MHC class 1 binding process

Answer 26

antigen processing to peptides in proteasome, peptide transport into endoplasmic reticulum (ER), then peptide binding by MHC class 1, and then MHC class 1 presents the peptide at cell surface

Question 27

MHC class 2 binding process

Answer 27

peptide production in phagolysosome, peptide binding by MHC class 2, MHC class 2 presents peptide at cell surface

Question 28

is peptide processing and presentation in MHC 1 molecules a continuous process?

Answer 28

yes, it is not a product of infection

Question 29

MHC class 2 molecules are expressed by what cells

Answer 29

professional antigen presenting cells

Question 30

what cells do not express MHC class 1 or 2 molecules

Answer 30

erythrocytes (RBCs)

Question 31

where are peptides presented by MHC class 2 molecules generated in

Answer 31

acidified intracellular vesicles

Question 32

which pathogens exploit the MHC class 2 pathway in order to hide from CD8 T cells

Answer 32

leprosy and tuberculosis

Question 33

what does the invariant chain do

Answer 33

blocks binding of peptides to MHC class 2 molecules in the ER until the time is right. when time is right DM facilitates the release of CLIP to allow peptide binding

Question 34

what does cross-presentation do

Answer 34

allows extracellular antigens to be presented by MHC class 1 if the virus has infected an extracellular component.

Question 35

which cells use MHC class 2 molecules

Answer 35

macrophages and dendritic cells

Question 36

what region of DNA is responsible for transplant rejection by T cells in unrelated patients

Answer 36

MHC complex on chromosome 6

Question 37

are HLAs the human version of MHCs

Answer 37

yes

Question 38

does HLA class 2 have more allotypes than class 1?

Answer 38

yes

Question 39

do HLA class 1 and 2 genes occupy different regions of the HLA complex

Answer 39

yes

Question 40

do MHC polymorphisms affect the binding and presentation of peptide antigens to T cells

Answer 40

yes

Question 41

does heterozygosity for MHC alleles confer a selective advantage

Answer 41

yes