Adaptive immunity - T cells

Question 1

What does the cell mediated response involve?
-Extracellular vs intracellular

Answer 1

Question 2

Where do cells, cytokines and pathogen antigens wash into?

Answer 2

-Lymphatic system

Question 3

Label structure of Lymph node.

Answer 3

Question 4

Label the structure of the spleen.
What does the white pulp contain?
What does it do?

Answer 4

The white pulp contains:
B cell corona -
Germinal centre – Antibody responses
Marginal zone – rich in macrophages and some B Cells
Periarteriolar sheath – mainly T cells

> Responds to antigens in the blood/ removes scenecent erythrocytes

Question 5

To get help dendritic cells need to express co-stimmulatory molecules and necessary chemokines to reach lymphocytes. What up regulates this?

Answer 5

-TLR which recognise the antigen > expresses co stimulatory molecule
-intracellular infections : IFNα and IFNβ

Question 6

What are the 2 types of T cells?

Answer 6

Question 7

Describe the recirculation of T-cells in lymph nodes.

Answer 7

1. T cells enter the lymph node via High endothelial venules into the paracortical area. (These venules have specialised endothelial cells which are cuboidal and express high levels of leukocyte receptors.)
2. In the paracortical area T Cells interact with dendritic cells presenting antigen
3. If they don’t encounter the antigen they recognise they continue out of the efferent lymph back into circulation

Question 8

How do dendrites activate naive T-helper cells?
-Activation
-Survival
-Differentiation

Answer 8

1. The T cell receptor recognises the antigen being presented and CD4 binds to the side of MHCII molecule - activation
2. Co stimulation occurs B7.1/2 bind and signal to CD28, this induces CD40L on the T cell which signals back to CD40 - survival
3. CD40L > CD40 instructs Polarising Cytokine release from antigen presenting cell then instructs the T cell what kind of T cell to differentiate into ( induce a variety of responses depending on which polarising cytokines they have been exposed to)
4. The T cell produces IL-2 to act on itself and proliferate activated T-cell – autocrine signalling

Question 9

What are polarising cytokines dependent on?

Answer 9

-The site and type of infection

Question 10

What does it mean for a T-helper cell to be anergic?

Answer 10

• A T-cell is only activated if there are co-stimmulatory molecules displayed as well as antigen.. without this they come anergic e.g. self molecules

Question 11

What is the polarising cytokine , transcription factor, cytokines produced and primary function for:
T- helper cell : 1 , 2 , 17, FH, reg

Answer 11

Question 12

What is the T-helper cell 1 response?

Answer 12

> enhance phagocytosis and antigen presentation. Responses enhance inflammation

Question 13

What is the T-helper cell 2 response?

Answer 13

> mediate defence which is independent of phagocytosis and directed against parasites
It doesn’t induce inflammation and promotes repair

Question 14

What is the T-helper cell 17 response?

Answer 14

> response to pro-inflammatory cytokines early in an immune response

Question 15

What is the T-helper cell reg response?

Answer 15

• Infection nears resolution > pathogen is removed > signal driving pro-inflammatory cytokine release disappears
• The tissue starts producing TGFβ.

-T cells enter the tissue > predominant cytokines drive them to become Tregs

• inhibit effector T cells and change macrophages to be anti-inflammatory

Question 16

What are cytotoxic T cells ? How are naive cytotoxic T cells activated?

Answer 16

> Directly kill cells which express non-self antigen on MHCI
CD8 receptor binds with antigen on MHC1 and activates
Naive CD8+ T cells do not require costimulation for proliferation and differentiation into cytotoxic effector cells.
Dendritic cell needs help from CD4+ T cell to activate CD8+ T cell
IL-2 from T-helper cell acts on cytotoxic cell to allow to proliferate - clonal expansion

Question 17

How do cytotoxic cells kill?

Answer 17

1. The activated CD8+ cell enters the infected tissue and recognises the antigen bound to MHCI
2. It contacts the cells and through binding of T Cell receptor to antigen and CD8+ to MHCI releases its granule contents.
3. Perforin produces a pore in the surface of the infected cell and granzyme is released into it.