Immune system Part 2

Question 1

Where do dendritic cells come from?

Answer 1

Majority of dendritique cells come from myeloide (innate)

Question 2

What is the role of dendritic cells

Answer 2

Similar kinda to the macrophage. However, where macrophages will clean up and alter, dendritic cells PRIMARY goal is the** alerting of the system. **
It does sampling and awaken the adaptive immune system.

It needs to be activated only when we are sure as the adaptive immune system is POWERFULL

Le but premier de la cellule dendritique est de présenter des antigènes provenant de pathogènes aux lymphocytes T

Question 3

How does the dendritic cell deal with a bacteria?

Answer 3

It acts in a similar way to a macrophage it takes the pathogen inside and puts it in a phago lysosome breaks it down and then create CMH-2 to present on surface

Important CMH2
CMH2!!!!

Question 4

True or False

La cellule dendritique produit des complexes majeurs d’histocompatibilité de classe I qui se lieront avec des fragments protéiques du pathogène ingéré

Answer 4

FALSE

Class 2 for ingested pathogen

Important CMH2
CMH2!!!!

Question 5

In terms of a CMH-2, what is an antigen?

Answer 5

The antigen is the part of the pathogen that is presented on the CMH

Question 6

Name the only cells in our body that can express CMH 2

Answer 6

Seuls les cellules dendritiques, les macrophages et les lymphocytes B expriment
des CMH de classe II

Question 7

True or false:
If a dentritic cell is infected by a virus it becomes unable to perform its action

Answer 7

False
Dendritic cells can also be infected by a virus or ingest a cell that is infected by a virus
The judicial can then move The virus fragments in their cytoplasm to degrade them and transform them in CMH-1

Question 8

What is the difference between a dendritic cells expressing CMH 1 and another one expressing CMH 2

Answer 8

Edendrich Excel expressing CMH 2 will have ingested a bacteria
On the other hand a cmh 1 will have ingested either a cell infected by a virus or had been infected by a virus itself
(It is rare that a virus infects the dendritic cells. So it is rare that we will find CMH1 on dendritic cells that came from an infection inside the IC. Instead, they take the infected cells, injest them and then produce and express CMH-1)

Remember: ALLL CELLS IN THE HUMAN BODY EXPRESS CMH-1

IF the cell has injected a pathogen, the antigen will be on CMH type 2

IF the pathogen has entered the cytoplasm, the antigen will be on CMH - 1

There are only 3 types of cells in the body that have CMH 2 (b lymphocytes, dendritique cells, macrophages)
All the cells of the human body have CMH-1

Question 9

What is a co stimulation molecule?

Answer 9

Echo simulation molecule is often found on dendritic cells and it is a necessary second signal to activate T cells
This is just to make sure that whatever cell sees this cmh actually needs to be activated

Question 10

In what region do the dendritic cells presents to the T cells

Answer 10

C’est dans le ganglion que la cellule dendritique pourra rencontrer le lymphocyte T

The meeting of the dendritic cell (cellule presentatrice d’antigene) and the adaptive immune system cell happens in the ganglions.

The adaptive immune cells are sleeping here, and they are shown the antigen.

Question 11

What are the two main cells of adaptive immune system?

Answer 11

1) Immunité cellulaire (lymphocyte T)
2) Immunité humorale (lymphocyte B)

Question 12

Explain how the T cell digitic cell interaction occurs in the ganglion

Answer 12

Need to fidn the right cells that expresses the right TCR

The antigen cannot just be floating to be recognized,
it must be bound to the CMH and well and co-stimulation molecule

The first activation happens from CMH+antigen
This is not sufficient. The T lymphocyte will not activate if there is not co-stimulation molecule

In fact, if there is no co-stim molecule, the t lymphocyte can even kill itself so it wont attack self cells

Must only activate against pathogens!!!

Question 13

D’où viennent les lymphocytes T?

Answer 13

Adaptive immune : Cellule progénitrice lymphoïde

Question 14

True or false colin every lymphocyte expresses a unique tcr receptors

Answer 14

true every T lymphocyte expresses an unique receptor that can recognize only one antigen
Given the specific character of T lymphocytes it is important to produce a lot of them so that they can recognize every possible antigen

Question 15

True or false:The lymphocytes can be dangerous because some of them can express receptors against self

Answer 15

False
For starters the majority that mature in the thymus that have TCR for self will be eliminated
Secondly it would be rare for A dendritic cell to express a cosimulating molecule along with a self cmh
Thirdly when dendritic cells only present self CMH without a co stimulating molecule the T lymphocytes could become inactivated or kill themselves

Question 16

What follows the activation of t lymphocytes?

Answer 16

If the antigen presenting cell possesses a second signal then A third differentiation signal in forms of cytokine will occur

t lymphocyte will proliferate and multiply

Question 17

What are the two types of t lymphocyte

Answer 17

Lymphocyte T « helper » (TH) CD4
Lymphocyte T cytotoxique CD8

Question 18

What is special in terms of activation between CD4 and CD8 cells

Answer 18

CD4T lymphocyte or T helpers will only recognize antigens presented on CMH 2

Question 19

What is the role of the third signal t lymphocyte proliferation

Answer 19

The third signal which is a cytokine is a signal of differentiation
It will determine whether the T cell will become a TH1TH2 TH17 or TFH cell

Question 20

If a patient has a high blood count of th 2 cells he is likely dealing with what

Answer 20

Likely dealing with an infection from a parasite because TH2 cells are important in recruitment of éosinophiles

Question 21

What is the difference in terms of presentation for CD4 cells when they reach the infection side versus when they are at the ganglion

Answer 21

The difference is that when CD4 cells are at the infection side they need to resee the aftergen that is the same antigen that they saw to get activated but the difference is that there is no need for co stimulating signal
And no need for a second signal the cmh 2 is sufficient

Question 22

True or false macrophages can activate CD4 cells

Answer 22

Macrophages cannot travel to ganglions to activate tea lymphocytes new one
So in that sense they cannot do the initial activation
However when the T lymphocyte is at the side of infection they can be activated either by macrophages or the digic cells since they both can express CMH 2 receptor

Question 23

What is the role of TH1 cells

Answer 23

TH1 cells are activated T lymphocyte CD4 lymphocytes
Their role is to help increase macrophage activity
This is done via the production of TH1 activating cytokines

Question 24

what is the role of cd four th 2 cells

Answer 24

After getting the CMH2 activation, it will release cytokines specific to the recruitment of eosinophiles

These are the ones that are important for Éosinophiles recruitment to combat certain parasites

Question 25

What is the role of CD17 lymphocytes

Answer 25

Sometimes we just need more bombs
TH17 help release IL17 which recruits more neutrophiles

Question 26

What is the main difference between CD4 and CD8 cells

In terms of activation

Answer 26

CD4 sells only recognize cmh 2
CD8 cells only recognize antigens on CMH 1
This means pathogens that have been intracytoplasmatic (virus)

Question 27

What is the main difference between CD4 and CD8 cells in terms of function

Answer 27

CD8 cells go to the side of infection not to help with the response but rather to kill pathogens infected
CD8 cells look specifically for CMH 1 and because all cells present cmh one it makes it great to kill cells that might have the virus
Once a CD8 cells finds its antigen it will kill it using granules which is very highly specific almost like a sniper (Adjacent cells do not get hurt)

Question 28

True or false:
Killing a cell infected by a virus through CD eight granules is sufficient to neutralize the virus

Answer 28

False
Killing the cell is not sufficient as the virus can infect another cell
Therefore the parts of the virus that are released in the environment will bind to antibodies to be neutralized