Lecture 8

Question 1

To innitiate immune responses, antigens are captured from their site of entry and concentrated in ____ lymphoid organs

Answer 1

secondary (peripheral)

Question 2

What type of antiens do T cells reconize and respond to?

Answer 2

Cell-associated; not soluble cell-free

Question 3

What is MHC restriction?

Answer 3

Receptors for CD4+ and CD8+ T cells are specific for peptide antigens that are displayed by MHC molecules

Question 4

What is antigen processing?

Answer 4

Generation of peptides from native proteins

Question 5

What are the two categories of major intracellular compartments?

Answer 5

1. cytosol
2. vesicular compartments

Question 6

Peptides derived from cytosol are transported into the ER loaded on ____

Answer 6

MHC-I

Question 7

What type of peptides are transported into the ER loaded on MHC-I

Answer 7

viruses and certain bacteria

Question 8

What type of T cell does MHC-I present its antigen to?

Answer 8

CD8

Question 9

What type of cell does MHC-II present its antigen to?

Answer 9

CD4

Question 10

What effect does presentation by MHC-I have on the cell?

Answer 10

Cell Death

Question 11

What effect does presentation by MHC-II have on the cell?

Answer 11

activation of microphage, activation of B cells to secrete Ig

Question 12

What is Cross-presentation?

Answer 12

the ability of certain APCs (mostly dendritic cells) to take up, process and present antigens from exogenous sources with MHC-I to CD8 T cells

Question 13

What is cross-priming?

Answer 13

the activation of naive CD8 T-cells into activated CD8 T-cells by the cross-presentation pathways

Question 14

What happens during the autophagy pathway?

Answer 14

• delivery of cytosolic antigens for presentation by MHC-II
• self-cytosolic proteins for the induction of tolerance to self antigens
• cytoplasmic proteins delivered into endocytic system (autophaosomes) for degradation in lysosomes

Question 15

What does the proteasome do in protein degradation in the cytosol

Answer 15

generates MHC-I presented peptides

Question 16

How are proteins in the cytosol tagged for degradation?

Answer 16

ubiquitin-proteasome system

Question 17

How does the ubiquitin-proteasome system work?

Answer 17

• several ubiquitin molecules are attached to a target protein
• lysine-linked ubiquitin chain is recognized by the proteasome
• protein is unfolded in the proteasome catalytic core and chopped into short peptides and released into the cytosol

Question 18

What are TAP-1 and TAP-2?

Answer 18

• they form a peptide transporter in the ER membrane
• peptides from the cytosol are transported by TAP into the ER before binding to MHC I