Secondary Lymphoid Organs

Question 1

What cells are lymphoid follicles loose networks of? What type of cells are they normally surrounded by?

Answer 1

Follicular dendritic cells (FDCs) surrounded by B cells

Question 2

Where in the body are dendritic cells produced?

What types of cells do dendritic cells present antigen to? Follicular dendritic cells?

Answer 2

Bone marrow

DC’s - T cells via MHC
FDCs - B cells

Question 3

What is the dark zone of the germinal center?

Answer 3

Area of non-proliferating, unactivated B cells that have been pushed to the side

Question 4

What is the light zone of the germinal center?

Answer 4

Area of proliferating, activated B cells

Question 5

What are the doorways through which B and T cells enter secondary lymphoid organs from blood?

Answer 5

High endothelial venules

Question 6

What types of cells line the walls of the marginal sinus in the LN’s and capture pathogens?

Answer 6

Macrophages

Question 7

What part of the LN are the HEV’s located in? What types of cells tend to accumulate there?

Answer 7

Paracortex

T cells, dendritic cells

Question 8

What type of antigen do follicular dendritic cells present?

Answer 8

Opsonized antigen

Question 9

What chemokine do follicular dendritic cells produce in the LN that attracts naive B cells? What happens if a B cell finds its cognate antigen?

Answer 9

CXCL13

If B cells finds its cognate, downregulates CXCL13 receptors, upregulates CCR7 receptor which directs B cell to region of activated Th cells

Question 10

What is an example of mucosal-associated lymphoid tissue located in small intestine which acts as a secondary lymphoid organ?

Answer 10

Peyer’s Patches

Question 11

What type of cell sits on top of a Peyer’s Patch and directs antigen into patch from small intestine?

Answer 11

M cell - does so through endosomes

Question 12

How do lymphocytes enter Peyer’s patches?

Answer 12

HEVs

Question 13

What % of circulating blood is in spleen? How long does it take for spleen to screen all of our blood for pathogens?

Answer 13

5%

30 minutes

Question 14

Where is blood entering the spleen diverted to? What cells line this space?

Answer 14

Marginal sinus - lined with macrophages which scavenge debris and invaders and resident dendritic cells that take up foreign antigens and prepare class II or class I MHC displays

Question 15

Where are naive B cells and T cells concentrated in the spleen?

Answer 15

B cells - region between PALS and marginal sinus

T cells - PALS

Question 16

Where do dendritic cells in marginal sinus go once they are activated?

Answer 16

PALS where T cells have gathered

Question 17

Where do Th cells activated by DC’s in PALS go once they are activated?

Answer 17

Lymphoid follicles to activate B cells

Question 18

What do T cells express once they emerge from thymus that guides them to HEV’s in lymph node? What are the HEV’s expressing that allows T cells to bind?

Answer 18

T cells express L-selectin, which binds GlyCAM-1 on HEV’s