Antigen Processing and Presentation

Question 1

what is cell mediated immunity?

Answer 1

an immune response mediated partly by CD4+ and CD8+ T cells

Question 2

what are the three antigen presenting cells?

Answer 2

dendritic cells, B cells, and macrophages

Question 3

what MHC class molecule presents to CD8+ T cells?

Answer 3

MHC class I

Question 4

are CD8+ T cells cytotoxic or helper?

Answer 4

cytotoxic

Question 5

are CD4+ T cells cytotoxic or helper?

Answer 5

helper

Question 6

what cells mediate the initial peptide antigen collection in the periphery, transport to lymph nodes, and presentation to naive T cells?

Answer 6

dendritic cells

Question 7

what is a dendritic cell’s main function?

Answer 7

to sample antigen in the local environment and bring it back to the draining regional lymph node to present to T cells

Question 8

how long can it take to initiate an immune response after an antigen is present in the periphery?

Answer 8

7-10 days because encounters are random

Question 9

what two signals does a antigen presenting cell need to provide to the T cell in addition to the peptide fragment?

Answer 9

costimulatory molecule
cytokines
produce these after danger signal sensed

Question 10

what are exogenous danger signals?

Answer 10

components of bacteria, viruses, fungi, foreign DNA or RNA that bind to specific pathogen recognition receptors on the antigen presenting cells

Question 11

what are endogenous danger signals?

Answer 11

components of dead cells, cytokines, acidic/hypoxic/hyperosmotic environments

Question 12

what functions as a danger signal in vaccines?

Answer 12

adjuvant

Question 13

what cells are the most efficient at activating naive T cells (of the three professional antigen presenting cells)?

Answer 13

dendritic cells

Question 14

macrophages ____ travel like dendritic cells and have a tendency to acquire antigen, _________________________________________

Answer 14

do not
remain in the same peripheral tissue location and present antigen to passing T cells

Question 15

what cytokines are macrophages a principle source of?

Answer 15

pro-inflammatory cytokines such as TNF-alpha and IL-1

Question 16

what cells do B cells primarily present antigen to?

Answer 16

differentiated effector T cells in secondary lymphoid organs

Question 17

true/false: all nucleated somatic cells express MHC class I molecules

Answer 17

true

Question 18

in general, how are antigens acquired in the extracellular environment usually dealt with?

Answer 18

MHC class II pathway, presented to CD4 cells

Question 19

how does the MHC class II pathway work (steps)?

Answer 19

uptake into vesicular compartments (endosome)
processing: endolysosome
MHC class II molecules made
processed peptides associated with MHC class II molecules in vesicles
expression on cell surface

Question 20

antigenic peptides presented on MHC class I molecules are, in general, derived from ________________ protein antigens

Answer 20

intracellular

Question 21

what are the steps of MHC class I antigen presentation?

Answer 21

production of proteins in cytosol
proteolytic degradation
transport from cytosol to ER
assembly
surface expression

Question 22

what is antigen cross-presentation?

Answer 22

when an extracellular antigen is processed and presented on an MHC class I molecule

Question 23

why is antigen cross-presentation important?

Answer 23

extracellular antigens can be presented to CD8+ T cells