Lymphocyte Traffic and Mucosal Immunity

Question 1

Lymphocyte movement in absence of inflammation or specific antigen responses

Answer 1

Naive lymphocytes circulate from generative lymphoid tissues through secondary lymphoid tissues via blood and lymph

Question 2

How antigen migrates from site of infection to lymph node

Answer 2

Dendritic cells pick up antigen, then migrate from site of infection to lymph node

Question 3

Where do naive B and T cells circulate?

Answer 3

Secondary lymphoid organs, such as lymph nodes

Question 4

High endothelial venules (HEVs)

Answer 4

Specialized capillaries of lymphoid tissues where lymphocytes exchange from the blood

Question 5

What do endothelial cells in HEVs lack?

Answer 5

Tight junctions: make it easier for lymphocytes to pass through

Question 6

Only what type of immune cells exit the blood and enter the secondary lymphoid tissues through HEVs?

Answer 6

Lymphocytes

Question 7

Migration into and out of lymph nodes: B and T cells

Answer 7

Enter via blood (HEV), leave via lymphatics

Question 8

Migration into and out of lymph nodes: APCs and antigen

Answer 8

Enter and leave via lymphatics

Question 9

Thoracic duct

Answer 9

Lymphatic system drains back into blood via thoracic duct and right lymphatic duct

Question 10

What causes leukocytes to exit the blood?

Answer 10

Binding to vascular endothelial cells causes them to stop and exit blood at sites of inflammation

Question 11

Leukocytes exiting blood: steps

Answer 11

1. Rolling
2. Integrin activation by chemokine
3. Arrest/adhesion
4. Transendothelial migration

Question 12

Adhesion molecules

Answer 12

Bind to leukocytes to stop them and enable them to exit blood
Families are based on structure

Question 13

Do immune cells use the same or different adhesion molecules to regulate their tissue migration?

Answer 13

Different, but overlapping

Question 14

Vasodilation

Answer 14

Increase of net blood flow resulting in heat, redness, and swelling/edema

Question 15

Transudate vs exudate

Answer 15

Transudate: fluid escaping the blood vessels during vasodilation
Exudate: extravascular fluid with high protein content, indicative of more severe inflammation

Question 16

Difference between edema and pus

Answer 16

Edema: less localized or contained
Pus: localized accumulation of white blood cells

Question 17

What happens during inflammation?

Answer 17

Cytokines promote adhesion molecule expression

Question 18

5 signs of inflammation

Answer 18

Heat
Redness
Swelling
Pain 
Loss of function

Question 19

What will effector lymphocytes do that naive lymphocytes don’t?

Answer 19

Enter tissues

Question 20

Neutrophils have short lifespans unless they do what?

Answer 20

Enter tissues during inflammation or storage in spleen, liver, or lungs

Question 21

Neutrophil distribution in the absence of inflammation

Answer 21

Few neutrophils in peripheral tissues except for marginated pools in spleen, liver, and lungs

Question 22

Does leukocyte migration across the vascular endothelial junction disrupt tight junctions?

Answer 22

No- leukocytes express proteins that interact with tight junction proteins

Question 23

Lymphocyte homing

Answer 23

Effector and memory lymphocytes home to various tissues depending on which adhesion molecules and chemokine receptors they express

Question 24

Mucins

Answer 24

Most mucosal tissues are covered with them
Highly glycosylated proteins
Block chemical insults
Trap bioactive molecules such as defensins and IgA

Question 25

Cilia’s role in the lungs

Answer 25

Move mucus and particles up the respiratory tract where they can be swallowed and eliminated

Question 26

Main mediator of mucosal immune system

Answer 26

IgA

Question 27

Poly Ig receptor

Answer 27

Mediates transcytosis of IgA across epithelial lining

Question 28

Reason why lung infections make it hard to breathe

Answer 28

When airways become inflamed, neutrophils and macrophages accumulate and block exchange of gases

Question 29

Peyer’s patches

Answer 29

Take up antigen from gut and transport it into draining lymph nodes

Question 30

M cells

Answer 30

Mucosal lining of gut: site of antigen entry

Immune cells in Peyer’s patches take up antigen that entered through M cells

Question 31

Transportation of antigen through M cells

Answer 31

Transcytosis enables transport of antigen through M cells

Antigen is then delivered directly to APCs and lymphocytes of mucosal immune system