Cells and Components of the Immune System

Question 1

Which MHC class is recognized by Cytotoxic T Lymphocytes (CD8+)?

Answer 1

MHC-I

Question 2

Which MHC class is recognized by Helper T Lymphocytes (CD4+)?

Answer 2

MHC-II

Question 3

Do Natural Killer cells recognize MHC presentation?

Answer 3

No, but they recognize the Class I MHC as a “don’t kill” signal

Question 4

What do neutrophils do?

Answer 4

phagocytose bacteria coated with IgG and IgM

Question 5

What do Mast Cells and Basophils release upon activation?

Answer 5

• Histamine
• Heparin
• Chemotactic Agents

Question 6

Where do immature T lymphocytes first enter the thymus?

Answer 6

the cortex

Question 7

Where are Hassall’s Corpuscles located?

Answer 7

-medulla of the thymus

Question 8

Where do lymphatics enter the lymph node?

Answer 8

on outer convex surface into subcapsular sinus

Question 9

Where are HEV’s located? What are they for?

Answer 9

• cortex of lymph nodes

- entrance point for lymphocytes

Question 10

What is located at the center of a B nodule in a lymph node?

Answer 10

Germinal center

Question 11

What makes up the buffy coat of blood?

Answer 11

• Platelets

- Leukocytes

Question 12

What cells are leukocytes (white blood cells)?

Answer 12

• Neutrophils
• Lymphocytes
• Monocytes
• Eosinophils
• Basophils

Question 13

What leukocytes are granulocytes?

Answer 13

• neutrophils
• Eosinophils
• Basophils

Question 14

What leukocytes are Agranulocytes?

Answer 14

• Lymphocytes

- Monocytes

Question 15

What are the histological markers of neutrophils?

Answer 15

• few granules

- three lobed nucleus

Question 16

What are the functions of eosinophils?

Answer 16

• killer of parasites
• not phagocytic: they release their enzymes via exocytosis
• also modulate allergic inflammation to counteract histamine etc

Question 17

What are the histological markers of lymphocytes?

Answer 17

• Large nucleus, a little bit bigger than RBCs

- Small amount of basophilic cytoplasm

Question 18

What kind of surface marker (CD) is on B lymphocytes?

Answer 18

CD20+

Question 19

What kind of stem cell do eosinophils, basophils, neutrophils, monocytes, erythrocytes, and platelets derive from?

Answer 19

-Myeloid stem cell

Question 20

What kind of stem cell do lymphocytes derive from?

Answer 20

-lymphoid stem cell

Question 21

Which antibodies act as receptors on the surface of B Lymphocytes?

Answer 21

IgM & IgD

Question 22

Humoral Immunity = ?

Answer 22

Antibodies & B Cells

Question 23

Cellular Immunity = ?

Answer 23

T Cells

Question 24

What chemicals stimulate Cytotoxic T Lymphocytes to undergo clonal expansion?

Answer 24

IL-2

gamma-interferon

Question 25

What's the difference between basophils and mast cells?

Answer 25

Basophils are still circulating, mast cells are in tissue

Question 26

What is the complement system?

Answer 26

- 20 proteins that work together to destroy invaders - humans born with defects in complement system don't live long - Classical pathway depends on antibodies

Question 27

Which protein initiates the "alternative" pathway for complement activation?

Answer 27

C3b

Question 28

How do complement proteins eventually destroy bacteria?

Answer 28

- C3bBb cleaves more C3 as well as C5 - C5b, C6, C7, and C8 form a stalk that anchors the membrane attack complex (MAC) in the bacterial cell wall - C9 comes along and makes a channel that opens a hole in the surface of the bacterium

Question 29

Which proteins on human cells prevents complement from destroying friendlies?

Answer 29

- MCP (clips C3b) | - DAF (decay accelerating factor) (accelerates degradation of C3bBb)

Question 30

What is a third complement activation pathway aside from the classical (antibody dependent) and alternative (antibody independent) pathways? What initiates this pathway?

Answer 30

- lectin activation pathway | - initiated by mannose-binding lectin (MBL)

Question 31

What does iC3b do?

Answer 31

- inactivated C3b - cannot form Membrane Attack Complex (MAC) - opsonizes invaders to facilitate phagocytosis by macrophages

Question 32

How do natural killer cells kill cells?

Answer 32

- induce apoptosis via an injection system - introduce granzyme B into target cell - NK cell interacts with Fas on surface of target, inducing apoptosis

Question 33

Where are proteins of the complement system produced?

Answer 33

Liver **think about cirrhosis

Question 34

What protein does C3bBb cleave?

Answer 34

C3 also C5

Question 35

What does the MASP protein do in the lectin activation pathway?

Answer 35

cleaves C3

Question 36

What do C3a and C5a do?

Answer 36

-act as chemoattractants to attract more macrophages and neutrophils

Question 37

Where does LPS come from? What does it do?

Answer 37

- Gram negative bacteria | - binds to receptors on primed macrophages and makes them angry