Immuno Test II, Lecture 6 Flashcards Preview

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What is cell mediated immunity?

due to the direct action of T cells

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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.

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How have T cells evolved?

To protect us against intracellular microbes (viruses and some bacteria)

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What do T cells have to help to mount?

A robust Ab-mediated humoral immune responses directed agains extracellular pathogens

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What can T cells not do?

Cannot directly recognize unprocessed Ags or bind to microbes

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How are Ags in host cells broken up?

Into...

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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

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Where are the T cells educated?

thymus

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T cells are either?

selected for survival or eliminated if self reactive

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What is the general function of different T cells?

each with different functions in the immune response that are dictated by cytokines produced

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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

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CD8+ cytotoxic T cells

recognize peptides associated with MHC class I molecules

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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.

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What needs to happen to T cells in order for them to carry our their function?

they need to be activated

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What is not sufficient to activate the T cells?

recognition of the peptide Ag by the TCR

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What are required in addition to recognition?

Co-stimulatory molecules, with co receptors involved in signaling events

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What does T cells activation lead to?

production of IL-2, which controls clonal expansion of specivic T cells

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What does IL-2 control?

clonal expansion of the specific T cell

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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

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What is IFN gamma produced by?

Th1 cells activates Mo

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What are Th2 cells involved in?

Helping B cells to develop into memory cells and plasma cells that produce antibodies

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What is IL-4 produced by?

Th2 cells

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What is IL-4 important for?

B cell proliferation

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How is B cell activated?

Self activated, but cannot advance without help from Th cells.

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What do B cells develop into?

memory cells and plasma cells

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plasma cells produce?

antibodies

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What is the TCR of conventional (alpha, beta T cells)?

It is composed of two polypeptide chains, alpha and beta, which have molecular wights of 50 and 39 kDa

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What are the genes coding for TCR polypeptide chains?

members of the Ig super family

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What does the T cell receptor complex consist of?

The TCR, the alpha,beta or gamma,epsilon dimer, in association with CD3

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What is CD3?

A signaling complex composed of gamma, epsilon, and delta

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What is a seperate signaling molecule made up of?

...

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What does CD4 on T cells bind to?

nonpolymorphic region of MHC class II on APCs restricting Th cells to recognizing only peptides presented on MHC class II molecules

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CD8 on cytolytic T cells binds to?

the non polymorphic region of MHC class I, restricting...

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Know what TCR complex looks like

Slide...

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Proteasome genes structure

TAP1, 2

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Look at Detailed map of Human

MHC

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Class I major

HLA-B, C, A

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Class I region minor

HLA G, F, E

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What is the significance of co dominant expression of both parental allels of each MHC gene are expressed?

increases number of different MHC molecules that can presesnt peptides to T cells

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What is the significance of polymorphic genes: many different alleles are in the population.

Ensures that different individuals are able to present and respond to different microbial peptides

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What is the significance of MHC expressing Cell types: Class II: dendrictic cells, macrophages, B cells

CD4+ helper T lymphocytes interact with dendritic cells, macrophages, B lymphocytes

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Class I all nucle

...

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What are the two classes of polymorphic MHC genes encode human leukocyte ?

Class I and II, that can bind peptides and are thus critical to Ag presentations

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What are class I genes?

HLA-A, -B, -C

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What doe class I genes do?

encode a polymorphic heavy chain which combines with beta2-micro-globulin and is expressed on the surfaces of all nucleated cells

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What does the heavy chains of class I genes have?

a binding groove for peptides to be recognized by T cells

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What are Class II genes?

HLA-D

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What are Class II genes encoded molecules?

(HLA-DP, -DR....

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What is that alpha chain of the class I molecules?

glycosylated (carbohydrate residues are not shown)

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What does the ribbon diagram show??

The stucture of the ex....

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What do the anchor residues on the peptides do?

Bind to residues in the class I and II grooves and vary for different MHC alleles.

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What are MHC class II molecules expressed on?

professional APCs, only B cells, dendritic cells and macrophages

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What are MHC class I molecules expressed on?

all nucleated cells

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What is expression of MHC class I and II modulated by?

cytokines

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What are peptides that bind to class I MHC molecules derived from?

viruses that have infected host cells and move as the complexes to the surfac (endogenous pathway)

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What doe petides that bind to class I MHC bind to?

recgonized bty CD8+ cytotoxic T lymphocytes CTL

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Ags and pathogens taken from the environment primarily present on?

MHC class II molecules to CD4+ helper T cells

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What are professional APCs?

B cells macrophages, dendritic cells... They are strongly expressed on MHC class I and II

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Dendritic cells recognize?

antigens at the gate..

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CD28 does what?

Binds dendritic cell and naive T cells with the costimulator B7