Immune Cells and Organs

Question 1

What are primary lymphoid organs? give example

Answer 1

organs where lymphocytes are produced

bone marrow and thymus

Question 2

What are secondary lymphoid organs? give examples

Answer 2

organs where lymphocytes can interact interact with antigens and other lymphocytes
splendid, lymph nodes, mucosal associated lymphoid tissue

Question 3

How is bone marrow different in foetus and adult?

Answer 3

foetus - all bone and liver + spleen have marrow or very cellular
adults - flat bone and end of long bones have marrow

Question 4

What happens to bone marrow and the thymus in infection?

Answer 4

bone marrow - increased WBC output

thymus - nothing

Question 5

What happens to the thymus with age?

Answer 5

decreased output and decreased new specificity production

Question 6

What is the lymphatic system and how is the immune system related?

Answer 6

drainage system of fluid between tissue cells to lymph

antigens collected in lymph and filtered through lymph nodes to be recognised

Question 7

What is a lymph node?

Answer 7

filter system that allows fluid to interact with lymphocytes to see if antigen is recognised

Question 8

How does blood enter a lymph node?

Answer 8

via artery
moves across HEV into node
follows cytokines

Question 9

What does MALT have the the spleen doesn’t?

Answer 9

HEV

Question 10

What does the spleen do?

Answer 10

filters antigens in the blood, RBC turnover

Question 11

What is the spleen split into?

Answer 11

red pulp = RBC
white pulp = WBC
- split into marginal zone, primary follicle = B cells and periarterial lymphatic sheath = T cells

Question 12

What does MALT do, alongside skin?

Answer 12

form a barrier

Question 13

What are the characteristics of MALT?

Answer 13

high SA, single layer of cells, heavily defended by immune system

Question 14

What are the characteristics of gut ALT?

Answer 14

villi, intraepithelial lymphocytes, lymphatic drainage, peyer’s patches

Question 15

What are peyer’s patches?

Answer 15

large aggregates of lymphocytes (predominantly B cells), with specialised areas of M cells

Question 16

What are M cells?

Answer 16

sample antigens in the gut and present to lymphocytes in the payer’s patches

Question 17

How does the structure of skin relate to the immune system?

Answer 17

lymphatic vessels and venules in the dermis
lymphocytes in the layers
epidermal Langerhans cells present antigens in lymph nodes after capturing from skin

Question 18

Summarise the process of extravasation of naive T cells into lymph nodes via the HEV

Answer 18

NTC roll along endothelium surface and bind by selection
reach the HEV which has chemokine signals on the surface
NTC has receptors for T cells so binds
delivers a signal to NTC to change integrin molecule conformation so higher affinity for binding
stops rolling and migrate through endothelium

Question 19

What are lymphocytes?

Answer 19

small cells with agranular cytoplasm and large nucleus

Question 20

What are CD markers?

Answer 20

surface molecules that are used to discriminate cell types

Question 21

What CD do all T cells express?
What T cells express CD4 or CD8 and what is the proportion?
What other T cells are there?

Answer 21

CD3
alpha-beta T cells
-2/3 = CD4
-1/3 = CD8
gamma-delta T cells

Question 22

What do CD4 T cells do?

Answer 22

T helper, regulatory, secrete cytokines

Question 23

What do CD8 T cell do?

Answer 23

cytotoxic, lyse infected cells, secrete cytokines

Question 24

How do T cells recognise antigens?

Answer 24

processed antigens presented on surface of another cell with a T cell receptor

Question 25

Give example of antigen presenting cells

Answer 25

dendritic, B cell, macrophage

Question 26

What CD do B cells present?

Answer 26

CD19, CD20

Question 27

What is the function of B cells?

Answer 27

produce antibodies, present antigen to CD4 T helper cells, recognise free antigen in body fluid or on CSM