Immune Cells and Organs

Question 1

What is a primary lymphoid organ? What are they?

Answer 1

Where lymphocytes are produced, bone marrow and thymus

Question 2

What is the production of lymphocytes called?

Answer 2

Lymphopoiesis

Question 3

What is is a secondary lymphoid organ? What are the secondary lymphoid organs? (4)

Answer 3

Where lymphocytes interact with antigens and other lymphocytes. Spleen, lymph nodes, mucosal associated lymphoid tissue (MALT), nasal associated lymphoid tissue (NALT)

Question 4

Overview of lymphocyte life cycle

Answer 4

Mature in primary lymphoid tissue, enter circulation, leave circulation and enter secondary lymphoid tissue and keep recirculating till they meet their antigen or die.

Question 5

How can defects in primary lymphoid tissue be treated?

Answer 5

Stem cell transplants

Question 6

Where is the thymus?

Answer 6

Below the thyroid gland

Question 7

How many lobes does the thymus have

Answer 7

Two, bi-lobed

Question 8

Where do regulatory T lymphocytes develop in the thymus?

Answer 8

Hassall’s corpuscles

Question 9

Affect of age on T cell output?

Answer 9

Same number of T cells, lower diversity

Question 10

As lymph fluid drains in what part of the lymph node does it come into contact with first?

Answer 10

The lymphoid follicles (mostly B cells)

Question 11

What are lymphoid follicles made up of primarily?

Answer 11

Mostly B cells

Question 12

Where do T cells tend to be in the lymph nodes?

Answer 12

Towards the inside

Question 13

When do germinal centres appear?

Answer 13

During an immune response

Question 14

What are germinal centres?

Answer 14

Rapidly proliferating lymphocytes (B I think)

Question 15

What are high endothelial venues (HEV)?

Answer 15

Where lymphocytes leave the circulation and enter the lymph node

Question 16

What do chemokine do?

Answer 16

Direct lymphocytes

Question 17

What do dendritic cells do?

Answer 17

Migrate through the lymph to the lymph nodes where they present antigens to the lymphocytes

Question 18

What is the primary purpose of the spleen?

Answer 18

To filter for antigens in the blood

Question 19

What is “white pulp” of the spleen?

Answer 19

Where lymphocytes are

Question 20

What brings blood into the spleen?

Answer 20

The splenic artery

Question 21

What is the periarterial lymphatic sheath? What lymphocyte is predominantly in it?

Answer 21

The space immediately adjacent to the splenic artery. T lymphocyte.

Question 22

What is adjacent to the per arterial lymphatic sheath? What form is it in?

Answer 22

The B cell area in follicles

Question 23

What susceptibility does a lack of spleen induce?

Answer 23

Infections with encapsulated bacteria

Question 24

What do germinal centres in the spleen indicate?

Answer 24

Infection

Question 25

What is a Peyer's patch? Where is it found?

Answer 25

Large aggregates of lymphocytes and is found in the gut associated lymphoid tissue. Contains germinal centres and are predominantly B cells.

Question 26

What is an M cell, where is it and what does it do?

Answer 26

It is a microfold, it is in the mucosal epithelium of the gut and samples antigens from the gut and delivers these antigens to the lymphocytes in the Peyer's patch.

Question 27

In the Peyer's patch, are B or T cells on the interior / exterior?

Answer 27

B cells are in the middle, T cells are the most outermost

Question 28

Whats are langerhans cells?

Answer 28

Dendritic cells of the skin and mucosa

Question 29

What do keratinocytes do?

Answer 29

Detect damage in the skin and secrete signalling molecules to communicate this

Question 30

Summarise what happens when a pathogen invades the epidermis

Answer 30

A dendritic cell will capture the pathogen and migrate to a lymph node and the appropriate lymphocytes will have to enter the lymph node to detect the antigen

Question 31

What can high endothelial venules (HEV's) do?

Answer 31

Arrest lymphocytes

Question 32

What guides a lymphocyte to the right high endothelial venule?

Answer 32

Chemokines

Question 33

Explain how T lymphocytes enter the HEV with reference to chemokines, integrin, ICAM1 and selectins

Answer 33

Selectins ensure a low affinity binding as the T lymphocyte rolls along the surface of a HEV. If a chemokine is present, this binds to the integrin on the lymphocyte changing its conformation. This causes a change to high affinity binding of the integrin to a molecule called ICAM1. This stops the rolling and the lymphocyte migrates into the tissue.

Question 34

What type of cell expresses CD3?

Answer 34

T cells

Question 35

What CD do all T cells express?

Answer 35

CD3

Question 36

What is CD3?

Answer 36

An integral part of the non variable part of the antigen specific receptor on T cells.

Question 37

What are the two types of T cell receptor and their relative percentages in the body?

Answer 37

Alphabeta (90%) and gammadelta (10%)

Question 38

What two CD types can alphabeta TCR's be split into and their proportions in the body?

Answer 38

CD4 (2/3) and CD8 (1/3)

Question 39

What are CD4 cells and what do they do?

Answer 39

T helper cells, regulatory T cells that secrete cytokines

Question 40

What are CD8 cells and what do they do?

Answer 40

Cytotoxic T cells, they lyse infected cells and secrete cytokines

Question 41

When can a T cell recognise an antigen?

Answer 41

Once it has been processed and presented on the surface of another cell using an MHC molecule

Question 42

What CD classes do B cells express?

Answer 42

19 and 20

Question 43

What MHC class do B cells express?

Answer 43

II

Question 44

What interaction do B cells and CD4 cells have?

Answer 44

B cells present their antigens to CD4 cells

Question 45

What effector function do B cells have?

Answer 45

Producing antibodies

Question 46

Can B cells recognise damaged antigens?

Answer 46

No

Question 47

Difference between B and T cell antigen recognition?

Answer 47

B cells do not have to have processed antigens presented to them

Question 48

What are the three APC's of the body?

Answer 48

Dendritic cells, B cells, and macrophages

Question 49

Whats special about follicular dendritic cells?

Answer 49

They present their antigen to B cells, only cells to do so

Question 50

Where are B cells predominantly found?

Answer 50

In the lymphoid tissue