Test 2: Antigen Capture and Presentation

Question 1

At what site do antigens accumulate?

Answer 1

lymph nodes

Question 2

How are T cells in lymphoid organs alerted there is an infection?

Answer 2

APC capture, process and transport antigens to T cells

Question 3

Where does recognition by T cells occur?

Answer 3

antigens are transported from tissue/mucosa to lymphoid organs and recognition occurs here

Question 4

Which is the majority of dendritic cells in tissues and lymphoid organs?

Answer 4

classical dendritic cells

Question 5

What is the process of capture and presentation of antigens by dendritic cells?

Answer 5

• Immature dendritic cells capture and process protein antigen
• dendritic cells get activated and then up regular chemokine receptors CCR7 and costimulatory molecules
• now, mature dendritic cells present protein antigens to T cells

Question 6

What determines the specific recognition of antigens by T cells?

Answer 6

major histocompatibility complex molecules

Question 7

How do T cells recognize peptide antigens?

Answer 7

MHC molecules on antigen presenting cells

Question 8

How many sets of MHC genes?

Answer 8

2
- class I MHC genes
- class II MHC genes

Question 9

What is the structure of class I MHC?

Answer 9

• membrane proteins contain a peptide binding cleft at the amino terminal
• Alpha chain associated with B2-microglobulin

Question 10

What is the structure of class II MHC?

Answer 10

• membrane proteins contain a peptide binding cleft at the amino terminal
• alpha and beta chains

Question 11

Why do CD8 T cells only recognize peptides presented by MHC class I?

Answer 11

alpha 3 (which is invariant portion of alpha chain) bings CD8 on CD8 T cells

Question 12

Why do CD4 T cells only recognize peptides presented by MHC class II?

Answer 12

beta 2 (invariant portion of beta chain) binds CD4 on CD4 T cells

Question 13

What does MHC polymorphism ensure?

Answer 13

• a population can deal with microbe diversity

Question 14

Where is each class of MHC molecules expressed?

Answer 14

• class I expressed on all nucleated cells
• class II expressed on antigen presenting cells and induced by IFNy

Question 15

What can T cells bind?
a. lipids
b. proteins
c. carbohydrates
d. nucleic acids

Answer 15

b. proteins

can only bind peptides derived from protein antigens

Question 16

What can MHC molecules bind?
a. lipids
b. proteins
c. carbohydrates
d. nucleic acids

Answer 16

ALL

Question 17

MHC consists of 2 sets of ______ genes.

Answer 17

polymorphic

Question 18

How long does the binding last of peptide binding to MHC?

Answer 18

binding last up to days to maximize interaction with T cells

Question 19

Where are extracellular proteins (like tumor and bacteria) processed?

Answer 19

processed in endoscope/lysosome and peptides displayed on MHC class II to CD4 cells

Question 20

Where are cytosolic proteins (like virus and bacteria that escape phagosome) processed?

Answer 20

processed by proteasome and endoplasmic reticulum and peptides displayed on MHC class I to CD8 cells

Question 21

How is optimization of responses to different microbes with different locations achieved?

Answer 21

• extracellular: CD4
• intracellular: CD8