I&d Development Of The Immune System And Immunological Tolerance

Front 1

What is a 'HSC'?

Back 1

A haematopoietic stem cell

Front 2

What is the potency of HSCs?

Back 2

Multipotent

Front 3

Where do HSCs arrive in foetal development?

Back 3

The yolk sac, then the foetal liver

Front 4

The yolk sac, then the foetal liver

Which cells arise from her in foetal development?

Back 4

Haematopoietic stem cells

Front 5

What are the two different development pathways for a HSC?

Back 5

Myeloid and lymphoid

Front 6

What effect does the cytokine G-CSF have in HSCs?

Back 6

It induces differentiation into granulocytes

Front 7

What effect does the cytokine M-CSF have on HSCs?

Back 7

Induces differentaiton into monoycytes

Front 8

Lymphocyte precursors undergo antigen-dependent/antigen-independent differentation within the microenvironments of the primary lymphoid organs.

Back 8

Antigen -INdependent

Front 9

Lymphocyte precursors that become immunocompetent cells are driven by antigen-dependent/antigen-independent processes in the secondary lymphoid organs to develop into memory cells or effectors of the immune response

Back 9

Antigen-dependent

Front 10

Which cytokine commenses differentation of bone marrow stem cells into B-cells?

Back 10

IL-7

Front 11

Bone marrow stem cells destined to become B cells initially express the cell surface molecule...and then rearrange...

Back 11

CD19 and then rearrange their antigen receptor (antibody) genes

Front 12

When are cells called 'pre-B-cells'?

Back 12

When they express a small amounts of antibody heavy chain in their cytoplasm

Front 13

Which MHC is expressed on B-cells?

Back 13

MHC Class II
AND
MHC Class I (as with ALL nucleated cells!)

Front 14

Only specialised cells express MHC class II on their cell surface T/F

Back 14

T

Front 15

Only specialised cells express MHC class I on their cell surface T/F

Back 15

False! All nucleated cells in the body express MHC class I! B-cels express MHC class II

Front 16

'The mature B-cels then leave the bone marrow to function in the...'

Back 16

secondary lymphoid tissues

Front 17

What are the primary lymphoid tisssues?

Back 17

The bone marrow and the thymus

Front 18

T-cell differentiation occurs in the...

Back 18

...thymus

Front 19

Immature T-cells in the thymus express both CD4 AND CD8, what is the name for this coexpression?

Back 19

'double-positive'

The T-cells are said to be 'double-positive T-cells'

Front 20

Immature T-cels in the thymus begin to express their antigen-specific TCR together with CD_ molecules.

Back 20

CD3 molecules

Front 21

Where do immature T-cells start off in the thymus? Where do they move through to?

Back 21

Start in the subcapsular outer cortex and migrate into the deep cortex

Front 22

What happens to T-cells in the deep cortex of the thymus?

Back 22

They lose expression of either CD4 OR CD8 to become single positive T-cells

Front 23

The T-cells leave the thymus and are seeded to the...

Back 23

periphery

Front 24

What are the three roles of the thymus wrt T-cells?

(Hint: Two are closely related)

Back 24

To produce many different T-cells with receptors that recognise foreign antigens (generation of receptor diversity)

Select T-cels so they can recognise the body's own MHC molecules (positive selection)

Eliminate those T-cells with antigen receptors reacting with self antigens (negative selection)

Front 25

What is 'positive selection' wrt T-cells in the thymus?

Back 25

It is when only T-cells that can recognise the body's own MHC molecules are selected

Front 26

What is 'negative selection' wrt T-cells in the thymus?

Back 26

When T-cells with antigen receptors that react with self antigens are eliminated

Front 27

Our own healthy cells are left alone because they do not express _____

Back 27

PAMPs!

Front 28

How are ageing cells, such as erythrocytes, flagged for phagocytosis?

Back 28

Because the cells are aged, they have damage to the carbohydrates on their surface. This allows recognition by phagocytes

Front 29

Apoptotic cells are also disposed of due to the recognition of a loss of ________ ________

Back 29

membrane symmetry

Front 30

When self-cells need to be disposed of, the complement mecahnism is normally activated T/F

Back 30

False

Our cells have complement inhibitory molecules on their surface to avoid this.

Front 31

What are the two levels of tolerance for self-antigens?

Back 31

Central and peripheral

Front 32

Results from the elimination of self-reactive cells ruing lymphocyte development

Back 32

Central tolerance

Front 33

What happens on thymic cortical epithelial cells?

Back 33

T-cells whose TCR has an affinity for self-MHC molecules

Front 34

T-cells whose TCR has an affinity for self-MHC molecules are positively selected by which type of cell?

Back 34

Thymic cortical epithelial cells

Front 35

Even T-cells that have been selected for their good affinity of self-MHC can be dangerous. Why?

Back 35

The TCRs could have a high affinity for a compled of self peptide AND self MHC. These are referred to as 'autoimmune T-cells'

Front 36

What are 'autoimmune T-cells'?

Back 36

T-cells where the TCRs has a high affinity for a compled of self peptide AND self MHC.

Front 37

Where are autoimmune T-cells disposed of? And by which cells?

Back 37

Disposed of in the thymic medulla, when they interact with dendritic cells and macrophages (negative selection)

Front 38

Disposed of in the thymic medulla, when they interact with dendritic cells and macrophages

Back 38

Autoimmune T-cells

Front 39

Negative selection of T-cells in the thymus leaves T-cells with a strong/weak affinity for self-MHC molecules

Back 39

Weak!


1009271110 - Weekend home (:

Front 40

In the periphery, T-cells that have been negatively selected in the thymus have the potential to recognise a complex of foreign peptide plus self MHC molecules, and to become activated if the affinity of the interaction exceeds a certain threshold

Back 40

.

Front 41

Peripheral tolerance prevents...

Back 41

Prevents harm from any self-reactive cells that manage to escape deletion in the primary lymphoid organs

Front 42

Prevents harm from any self-reactive cells that manage to escape deletion in the primary lymphoid organs

Back 42

Peripheral tolerance

Front 43

Why do some self-reactive cells manage to escape detection in the primary lymphoid organs?

Back 43

Not all self-antigens are present IN the primary lymphoid organs

Front 44

Lymphocytes in the periphery are normally kept in an unresponsive state though...

Back 44

...clonal anergy

Front 45

A lack of reaction by the body's defense mechanisms to foreign substances, and consists of a direct induction of peripheral lymphocyte tolerance

Back 45

Clonal anergy

Front 46

What is clonal anergy?

Back 46

a lack of reaction by the body's defense mechanisms to foreign substances, and consists of a direct induction of peripheral lymphocyte tolerance

Front 47

What signals are necessary for activating lymphocytes in the periphery?

Back 47

Pathogen-triggered costimulatory signals

Front 48

Potentially autoreactive lymphocytes can also be suppressed by...

Back 48

...regulatory T-cells