Chapter 12

Question 1

Functions of antibodies

Answer 1

1. complement activation –> lysis of microbes, phagocytosis, inflammation
2. neutralization of microbes/toxins
3. opsonization and phagocytosis
4. antibody-dependent cytotoxicity

Question 2

Functions of IgG

Answer 2

opsonization
activation of complement

neonatal immunity

feedback inhibition of B cell activation

Question 3

IgM functions

Answer 3

complement activation

antigen receptor of naive B cells

Question 4

Functions of IgA

Answer 4

mucosal immunity

Question 5

Functions of IgE

Answer 5

cytoxicity involving eosinophils

mast cell degranulation

Question 6

IgD functions

Answer 6

antigen receptor of naive B cells

Question 7

Explain the opsonization and phagocytosis process

Answer 7

IgG binds microbes
Fc receptors on phagocytes recognize IgG

Fc signals to cell to promote phagocytosis

Question 8

What types of cells can kill targets that are coated with antibodies?

Answer 8

NK cells and Eosinophils

Question 9

Which Ig do NK cells recognize?

Answer 9

IgG

Question 10

Which type of Ig do Eosinophils recognize?

Answer 10

IgE

Question 11

Fc-gamma receptor

Answer 11

Found on NK cells

Recognizes Fc region of IgG to kill antibody coated cells

Question 12

Fc-epsilon

Answer 12

Recognizes the Fc portion of IgE bound to helminthic parasites

found on eosinophils which kill the parasites

Question 13

Zymogen

Answer 13

protein who gains proteolytic activity after being cleaved by another protease

Question 14

How do normal host cells evade the complement system?

Answer 14

They have inhibitory regulatory proteins present on their membranes

Question 15

Classical complement pathway

Answer 15

activated by antibodies (IgG and IgM) bound to antigen

Question 16

Alternative complement pathway

Answer 16

activated on microbial cell surfaces in the absence of antibody

Question 17

lectin complement pathway

Answer 17

activated by plasma lectin that binds to mannose receptors on the surface of microbes

mannose = PAMP

Question 18

a (in complement system)

Answer 18

small product

Question 19

b (complement system)

Answer 19

larger product

Question 20

MAC

Answer 20

membrane attack complex of the complement system

Question 21

C3 convertase

Answer 21

catalyzes proteolysis of C3 to C3a and C3b

Question 22

C3b

Answer 22

Binds to microbe!

Question 23

C3a

Answer 23

floats Away

chemoattractant

Question 24

T or F

C1 must bind to two or more Fc portions to initiate the complement cascade.

Answer 24

T

Question 25

Can C1 bind to soluble IgM?

Answer 25

No - bust bind after IgM binds to surface-bound antigens

Question 26

How can C1 bind to IgG?

Answer 26

Can bind to Fc regions of two adjacent surface bound IgG molecules

Question 27

C5 convertase

Answer 27

converts C5 to C5 a and C5b

Question 28

C5a

Answer 28

chemoattractant --> inflammation

Question 29

C5b

Answer 29

binds and builds up

Question 30

C6, C7, C8

Answer 30

bind in sequential order | must be bound for MAC to form

Question 31

How does the MAC form?

Answer 31

C9 molecules polymerize around the complement complex to create a pore

Question 32

What are the 4 regulators of complement activation?

Answer 32

1. Regulation of C1 by C1 inhibitor 2. Inhibition of the formation of C3 convertase 3. Proteolytic cleavage of C3b --> iC3b 4. Inhibition of the MAC

Question 33

Functions of complement

Answer 33

1. C3b opsonization --> phagocytosis 2. C5a and C3a recruit leukocytes and promote inflammation 3. MAC lyses cells

Question 34

where is IgA produced?

Answer 34

by plasma cells in the lamina propria of mucosal tissue

Question 35

How is IgA transported into the lumen of mucosa lined organs?

Answer 35

1. IgA binds to the poly-Ig receptor (base of epi cell) 2. Complex actively transported through cell 3. IgA released into lumen by proteolytic cleavage

Question 36

Transcytosis

Answer 36

process of active transport through a cell mechanism of IgA transport into the lumen of mucosally lined organs

Question 37

What is responsible for making IgA a dimer?

Answer 37

J chain

Question 38

Can monomeric IgA be transcytosed?

Answer 38

no