Immuno Test II, Lecture 6 Flashcards
Where did the cell mediated immunity term evolve from?
The finding that immunity to intracellular pathogens could be transferred to other animals by immune cells from infection-recovered animal.
What is cell mediated immunity?
due to the direct action of T cells
How have T cells evolved?
To protect us against intracellular microbes (viruses and some bacteria)
What do T cells have to help to mount?
A robust Ab-mediated humoral immune responses directed agains extracellular pathogens
What can T cells not do?
Cannot directly recognize unprocessed Ags or bind to microbes
How are Ags in host cells broken up?
Into…
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…
…
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Each T cell recognizes only one specific foreign peptide, how does the body over come this?
but there is a large TCR repertoire generated in the body
Where are the T cells educated?
thymus
T cells are either?
selected for survival or eliminated if self reactive
What is the general function of different T cells?
each with different functions in the immune response that are dictated by cytokines produced
CD4+ T helper cells recognize?
peptide Ags in the context of MHC class II molecules that are expressed by dendritic cells, Mo, and B cells
CD8+ cytotoxic T cells
recognize peptides associated with MHC class I molecules
What does the CD4 and CD8 attach to?
the non-polymorphic (non variant) part of the MHC class II and MHC class I molecules, respectively.
What needs to happen to T cells in order for them to carry our their function?
they need to be activated
What is not sufficient to activate the T cells?
recognition of the peptide Ag by the TCR
What are required in addition to recognition?
Co-stimulatory molecules, with co receptors involved in signaling events
What does T cells activation lead to?
production of IL-2, which controls clonal expansion of specivic T cells
What does IL-2 control?
clonal expansion of the specific T cell
What does Th1 do?
helps Mo to get rid of intracellular microbes and help the development of cytotoxic T cells to kill virus infected cells
What is IFN gamma produced by?
Th1 cells activates Mo
What are Th2 cells involved in?
Helping B cells to develop into memory cells and plasma cells that produce antibodies
What is IL-4 produced by?
Th2 cells