Antigen processing and presentation Flashcards
Understand which cells present antigen.
Dendritic/B cells/macrophage
What is a professional APC?
ability to present antigen in the context of MHC II
What are unique characteristics of professional APCs?
present antigen in the context of MHC II
What makes a dendritic cell unique among the professional APCs?
only APC that can activate T cells
What are the differences between an immature and mature dendritic cell.
Immature- low surface MHCII, increased endocytosis, low cytokine secretions
Mature- increased surface MHCII, decreased endocytosis, increased cytokine secretions
How does the B present antigen to a T cell and get help from the same T cell?
B cell presents antigen in the context of MHC II; T cell recognizes it and sends a signal to B cell, B cell then sends a second signal to the T cell to activate it
Understand processing of exogenous antigens
uptake (pahgocytosis); degradation (phagolysosome); complex formation of MHC II; presentation on MHC II on APC
Understand processing of endogenous antigens
uptake (intracellular proteins, viruses, intracellular bacteria); degradation by ubiquitin and proteosome; complex formation of MHC I (loaded in the ER); presentation of MHC I on nucleated cells
What kinds of cells process which antigen?
APC- exogenous; macrophages/neutrophils- endogenous
Where is the protein antigen processed with exogenous antigen? Endogenous antigen?
exogenous- phagolysosome
endogenous- within cytoplasm
Understand the proteins and organelles involved in antigen processing.
exogenous- phagosome fusing with lysosome; MHC class I and II; golgi apparatus endogenous- proteosomes, golgi and ER
On what cells is MHC I found?
nucleated cells
What kind of antigen does MHC I present?
endogenous; viral/intracellular organisms
What cell type does MHC I present to?
CD8 cytotoxic cells
What is the outcome of successful presentation via MHC I?
destruction of the cell via apoptosis
On what cells is MHC II found?
only on APC
What kind of antigen does MHC II present?
exogenous; ex.- bacterial, fungal
What cell type does MHC II present to?
CD4 helper T cells
What is the outcome of successful presentation via MHC II?
activation of CD4 helper T cells
What is cross priming? (cross presentation)
ex.- viruses; initially endogenous; with cell death virus becomes exogenous; present on MHC I and MHC II
