Self, Non-self Discrimination Immune System Flashcards Preview

MD2- Neuroscience Block > Self, Non-self Discrimination Immune System > Flashcards

Flashcards in Self, Non-self Discrimination Immune System Deck (13):
1

where is central tolerance acquired for B cells?
T lymphocytes?

bone marrow
thymus

2

where is peripheral tolerance acquired?

peripheral tissues and secondary lymphoid organs (spleen, lymph nodes)

3

what are the four mechanisms used to induce tolerance?

1. delete (eliminate problem(
2. anergize (switch off problem)
3. ignore (ignore the problem)
4. regulate (contain the problem)

4

how is b cell tolerance exerted centrally? peripherally?

in terms of efficiency, how does it compare to t cell tolerance?

central tolerance
-anergy
-deletion

peripheral
-ignorance, anergy, death
-lack of costimulation by T-cells

B cell tolerance less efficient than t cell tolerance.

5

2 signals for mature B cells to respond and survive?

1. signals via surface Ig-Ag interaction (cross-linking)

2. T cell help via CD40 ligand and some cytokines

without t cell interaction, b cells have very short lifespan.

6

what happens when people lack cd40L for B cell stimulation?

cant generate an appropriate immune response. tend see hyper IgM levels.

7

t cell development occurs in the [...]. at this stage of early development immature t cells carry both [...] and [...] receptors.

thymus
Cd4+ and Cd8+ co-receptors (double positive)

8

following expression of a TCP, double positive thymocytes next undergo two types of selection processes....

positive selection: thymocytes that recognize self-antigen and tolerate it, are selected to survive

negative selection: removal of immature thymocytes that have strong reactivity to self-antigen

9

t cell selection is dependant on receptor affinity for ?

self pMHC (sweet spot is between engaging too well and insufficient level of engagement).

10

Some proteins are only expressed in specific tissues/in the periphery. We must ensure thymocytes are exposed to them in the thymus:
Tissue specific antigens are expressed in the thymus under the control of [...] (an autoimmune regulator of expression).

Patients with mutation of AIRE might present with?

AIRE transcription factor

autoimmunity. potentially multiple autoimmune diseases.

11

Just as naiive B cells require stimulation from CD40L and surface Ag-Ig interaction, naiive T cells require two signals for activation and proliferation....

1) TCR-peptide MHC interaction

2) Co-stimulation (eg. CD28 with CD80/86)

NB: both signals must act together to allow proliferation/differentiation or else inactivation/tolerance results.

12

[....] are the most prominent suppressors of immune function (in regulating immune response).

[...] are derived from the thymus during t cell development..

[...] are derived following activation of naiive CD4 t cells in presence of TGF-beta. Express [...] and inhibit co-stimulation.

Tregs

nTregs (immunosuppressive against self-reactive T cells)

iTregs
CTLA4 (inhibitor of t cell responses)

13

how does CTLA4 inhibit costimulation

CTLA4 binds B7 receptor on APC more avidly than CD28