Antigen Processing and Presentation Flashcards
what is cell mediated immunity?
an immune response mediated partly by CD4+ and CD8+ T cells
what are the three antigen presenting cells?
dendritic cells, B cells, and macrophages
what MHC class molecule presents to CD8+ T cells?
MHC class I
are CD8+ T cells cytotoxic or helper?
cytotoxic
are CD4+ T cells cytotoxic or helper?
helper
what cells mediate the initial peptide antigen collection in the periphery, transport to lymph nodes, and presentation to naive T cells?
dendritic cells
what is a dendritic cell’s main function?
to sample antigen in the local environment and bring it back to the draining regional lymph node to present to T cells
how long can it take to initiate an immune response after an antigen is present in the periphery?
7-10 days because encounters are random
what two signals does a antigen presenting cell need to provide to the T cell in addition to the peptide fragment?
costimulatory molecule
cytokines
produce these after danger signal sensed
what are exogenous danger signals?
components of bacteria, viruses, fungi, foreign DNA or RNA that bind to specific pathogen recognition receptors on the antigen presenting cells
what are endogenous danger signals?
components of dead cells, cytokines, acidic/hypoxic/hyperosmotic environments
what functions as a danger signal in vaccines?
adjuvant
what cells are the most efficient at activating naive T cells (of the three professional antigen presenting cells)?
dendritic cells
macrophages ____ travel like dendritic cells and have a tendency to acquire antigen, _________________________________________
do not
remain in the same peripheral tissue location and present antigen to passing T cells
what cytokines are macrophages a principle source of?
pro-inflammatory cytokines such as TNF-alpha and IL-1
what cells do B cells primarily present antigen to?
differentiated effector T cells in secondary lymphoid organs
true/false: all nucleated somatic cells express MHC class I molecules
true
in general, how are antigens acquired in the extracellular environment usually dealt with?
MHC class II pathway, presented to CD4 cells
how does the MHC class II pathway work (steps)?
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
antigenic peptides presented on MHC class I molecules are, in general, derived from ________________ protein antigens
intracellular
what are the steps of MHC class I antigen presentation?
production of proteins in cytosol
proteolytic degradation
transport from cytosol to ER
assembly
surface expression
what is antigen cross-presentation?
when an extracellular antigen is processed and presented on an MHC class I molecule
why is antigen cross-presentation important?
extracellular antigens can be presented to CD8+ T cells
