Antigen Presenting Cells

Question 1

Which are the ONLY cells wich are able to activate naive T cells?

Those who have never been in contact with an antigen before.

Answer 1

Dentritic cells

The mos important APC

Question 2

What determines if a T cell will have a cytotoxic or helper response?

Answer 2

The type of MHC they encounter.
(CD8) MHCI - cytotoxic
(CD4) MHCII - helper

Question 3

Where are inactivate Dentritic Cells?

Answer 3

In peripheral areas

Skin, Mucosa…

Connective tissue, epithelia

Question 4

Where are DC in the spleen?

Answer 4

Cortical regions

Question 5

Where are macrophages in the spleen?

Answer 5

Marginal sinus and medullary cords

Question 6

Where are B cells in the spleen?

Answer 6

Follicles

Question 7

Why do mature dentritic cells stop their capacity to uptake antigens?

Answer 7

As in it’s way to the lymph node it may encounter self antigens. By this way the chances of producing an autoimmune reaction are reduced.

Question 8

What type of molecules stimulate the movement of cells?

Give an example

Answer 8

Chemokines

CCR7

Binds to CCL19 and CCL21

Question 9

Which are the only cells able to do cross presentation (cross priming)?

Answer 9

cDC 1

Conventional Dentritic Cells

So they are the only ones able to activate cytotoxic responses (CD8)

Question 10

What’s cross priming?

Answer 10

The abiliity to present Ag in MHCI and therebefore present them to cytotoxic T cells.

Question 11

Which dentritic cells come from a lymphoid progenitor?

Answer 11

pDC

Plasmacytoid dendritic cells.

Question 12

What do pDC produce?

Answer 12

Many proteins as interferon type 1

Activator of cytokines after the contact with viruses.

Question 13

Which cells participate in antiviral innate immunity?

Answer 13

pDC

Plasmacytoid Dentritic Cell

Question 14

Which cells express TNFalpha and ROS?

Answer 14

Monocyte-derived DC

Question 15

Which cells are the first immunological barrier to the external enviorenment?

Answer 15

Langerhans cells

Question 16

Pathway of antigen presentation of MHC I and II.

Answer 16

MHC I - endogenous processing
MHC II - exogenous processing

Question 17

What pathway is presented in all cells?

Answer 17

Endogenous pathway

All cells can be infected by viruses and they alarm the immune system.

Question 18

How is the threat of presenting self-antigens mitigated during protein processing?

This is to avoid autoimmunity.

Answer 18

Through the change of the proteosome to an immunoproteosome.

Only found in infected cells and triggered by interferon gamma.

Question 19

In what organelle is MHC generated?

Answer 19

In the RER.

Question 20

How is the transmembrane protein wich allows the transport of antigens insde the RER called?

Answer 20

TAP

Transporter of antigen processed molecules

Question 21

Which enzyme trims the peptide so it’s the right size (8-10 Aa)?

Answer 21

ERAP1

Endoplasmic Reticulum Amino Peptidase

Question 22

Which cells detect the abscence of MHC?

This happens mostly in cells infected by virus.

Answer 22

Natural Killer Cells

Question 23

What is the function of the Invariant chain?

Answer 23

Transport of MHCII to endocytic vesicles (where the peptides are) and prevents peptides from binding to MHCII too early.

Question 24

Function of HLA-DO and HLA-DM.

Answer 24

HLA-DO (oscuro) eliminates the CLIP.
HLA-DM (mañana) exchanges the CLIP for a peptide fragment.

Question 25

Which cells express MHC I?
And MHC II?

Answer 25

MHCI - All nucleated cells.
MHC II - only APCs.