Humoral Immunity

Question 1

which Ig is main defense in saliva, which cells produce it, and how do they act

Answer 1

IgA, plasma cells produce IgA in salivary glands and inhibit attachment of oral species to epithelial cells

Question 2

what are the three function of antibodies or Ig that don’t involve complement system

Answer 2

• neutralization of microbes and toxins
• opsonization and phagocytosis of microbes
• antibody-dependent cellular cytotoxicity (ADCC)

Question 3

what are the three function of antibodies or Ig that use complement activation

Answer 3

• lysis of microbes
• phagocytosis of microbes opsonized with complement fragments
• inflammation

Question 4

which region(s) of Ig is needed for neutralization

Answer 4

variable region

Question 5

which region(s) of Ig is needed for elimination

Answer 5

variable and constant region

Question 6

both neutralization and elimination are triggered by what:

Answer 6

binding of antigen to variable regions

Question 7

what kind of antibodies are the most effective

Answer 7

antibodies with high affinity for antigens

Question 8

IgG is generally found where

Answer 8

blood

Question 9

IgA is generally found where

Answer 9

mucosa

Question 10

for neutralization, binding molecules on microbes required for infection cells/tissues does what

Answer 10

blocks colonization

Question 11

antibody binding microbes can stop it from doing what two things

Answer 11

passing through epithelial barriers, and binding to individual cells to infect them

Question 12

T/F antibody can bind to toxins and block binding to cellular receptor

Answer 12

True

Question 13

what does FcR bind

Answer 13

constant region of Ig

Question 14

what happens to FcR that results in cellular activation

Answer 14

FcR clustering

Question 15

clustering of FcR requires recognition of what

Answer 15

multivalent antigen by Ig

Question 16

FcyRI/IIA promotes what

Answer 16

phagocytosis of Ig-coated microbes by phagocytes (IgG)

Question 17

FcyRIIIA (CD16) induces what

Answer 17

killing of Ig-coated infected cells by NK cells (ADCC)

Question 18

FceRI induces what

Answer 18

degranulation of mast cells (IgE)

Question 19

what is meant by multivalent antigen

Answer 19

antigen that can bind multiple Ig

Question 20

how is helminth killed

Answer 20

1. FceRI binds Fc portion of IgE-coated helminth
2. triggers degranulation of toxic mediators that kill helminth

Question 21

do FceRI and IgE target infected cells when killing helminth?

Answer 21

nope. do not target infected cells

Question 22

which cells are coated with IgE specific for allergens, and with FcR is involved

Answer 22

mast cells and basophils
FceRI

Question 23

what happens to FceRI that is bound to IgE by multivalent allergen that triggers degranulation

Answer 23

clustering of FceRI

Question 24

activation of complement involves what

Answer 24

the sequential proteolysis of proteins to generate enzymes (zymogens)with proteolytic activity

Question 25

products of complement activation covalently bind what:

Answer 25

-microbial surface - Ab bound to microbes - Ab bound to tissues

Question 26

in the complement pathway, plasma proteins are activated by what

Answer 26

microbes

Question 27

what does the complement pathway result in

Answer 27

phagocytosis, inflammation, and destruction of microbes

Question 28

mammalian cells express proteins that block what

Answer 28

block complement fixation and subsequent activation

Question 29

what are the three complement pathways

Answer 29

1. classical 2. alternative 3. lectin

Question 30

what is the alternative pathway triggered by

Answer 30

C3b binding to microbial surfaces

Question 31

how do Factor D and Factor B interact in alternative pathway

Answer 31

Factor D cleaves Factor B

Question 32

what does Bb do in alternative pathway

Answer 32

an enzyme able to cleave C3 into C3 and C3b

Question 33

what is C3b also known as

Answer 33

opsonin

Question 34

what is C3a also known as

Answer 34

anaphylatoxin (leukocyte recruitment and activation)

Question 35

what is classical pathway triggered by

Answer 35

binding of C1 to microbe-bound antibodies (IgG, IgM)

Question 36

what is the first component of the MAC (membrane attack complex)

Answer 36

C5b

Question 37

what is the lectin pathway triggered by

Answer 37

binding of circulating lectins (MBL) to microbe polysaccharides (mannose)

Question 38

what is the most important step in complement activation

Answer 38

cleavage of C3 by C3 convertase

Question 39

what is the net result of the complement pathway

Answer 39

coating of microbes with C3b (opsonin)

Question 40

what is the late step of the complement pathway

Answer 40

formation of the membrane attack complex (MAC)

Question 41

which proteins are involved with the MAC

Answer 41

C5b, C6, C7, C8 and C9

Question 42

what specifically does C9 do

Answer 42

multiple C9 form a pore - this causes osmotic swelling because H2O rushes into the cell

Question 43

which microbe is especially susceptible to the MAC and why

Answer 43

Neisseria due to thin cell wall

Question 44

how is complement activation regulated

Answer 44

plasma and membrane proteins prevent complement fixation at the surface of mammalian cells

Question 45

what are the three general function of the complement system

Answer 45

1. opsonization and phagocytosis (C3b protein) 2. complement-mediated cytolysis (MAC causes osmotic lysis of microbes) 3. stimulation of inflammatory reactions (anaphylatoxins)

Question 46

which anaphylatoxin is most potent

Answer 46

C5a then C3a, then C4a

Question 47

what do the anaphylatoxins increase

Answer 47

extravasation (movement of WBCs into tissues) of plasma proteins and monocyte/neutrophils - which leads to increase in microbicidal activities