Antibodies and Complements

Question 1

features of antibodies

Answer 1

1. bind variety of antigens
2. exquisite discrimination of similar antigens
3. bind antigens strongly
4. recognize antigens in native form

Question 2

functions of antibodies

Answer 2

1. opsonization
2. complement fixation
3. direct neutralization

Question 3

opsonization

Answer 3

tag microbes for phagocytosis

Question 4

complement fixation

Answer 4

recruit complement system to destroy microbes or infected cells

Question 5

direct neutralization

Answer 5

bind toxins in the blood/facilitate removal of toxins

Question 6

what prevents bacteria from adhering to cell wall

Answer 6

direct neutralization

Question 7

what is the major Ig in serum?

Answer 7

IgG (70-75% of all Ig)

Question 8

function of IgG

Answer 8

1. provide neonatal immunity
2. role in immune memory
3. is basic structure for all Ig’s

Question 9

what Ig is less than 1% of circulating Ig’s

Answer 9

IgD

Question 10

function of IgD

Answer 10

major component of B-cell surface (B-cell receptor)

Question 11

function of IgE

Answer 11

1. kills parasites
2. contributes to allergic reactions
3. activates mast cells, causes release of inflammatory granules

Question 12

what Ig is on surface of basophils and mast cells

Answer 12

IgE

Question 13

what Ig is most abundant in mouth (when no infection present)?

Answer 13

IgA

Question 14

IgA

Answer 14

secreted into saliva

usually a dimer

Question 15

what Ig is most abundant in mouth (when infection is present)?

Answer 15

IgG

Question 16

what is the first secreted antibody in response to an antigen?

Answer 16

IgM

Question 17

IgM

Answer 17

exists as a pentamer of Ig cells

can class shift from IgM -> IgG**

Question 18

antibodies?

Answer 18

IgG, IgA, IgM, IgE, IgD

i always just remember GAMED

Question 19

complement system

Answer 19

part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear pathogens from an organism

Question 20

complement system contributes to:

Answer 20

1. inflammatory reactions
2. chemotaxis
3. clearance of immune complexes
4. cellular activation
5. antimicrobial defenses

Question 21

central component

Answer 21

C3

Question 22

later components

Answer 22

[C5], [C6, C7, C8] [C9]

Question 23

proenzyme

Answer 23

inactive enzyme (activated via proteolytic cleavage)

many complement factors are proenzymes

Question 24

complement opsonization

Answer 24

1. complement fragments coat surface of target
2. induce phagocytosis

3, complement receptors ON phagocytic cells mediate phagocytosis

Question 25

complements involved in opsonization

Answer 25

C3b, iC3b, C4b

Question 26

complement chemotaxis

Answer 26

1. small fragments of complements form concentration gradient 2. stimulate immune cells to move towards infection

Question 27

complements involved in chemotaxis

Answer 27

C5a and C3a

Question 28

complement lysis of target cells

Answer 28

activation results in MAC (membrane attack complex)

Question 29

function of MAC (membrane attack complex)

Answer 29

causes holes in cell membrane to cause lysis

Question 30

complements involved in lysis

Answer 30

C5b (specifically critical for cytolysis)

Question 31

complement activators

Answer 31

1. classical pathway activators | 2. alternative pathway activators

Question 32

which complement activator creates antibody/antigen complexes?

Answer 32

classical pathway activators

Question 33

which complement activator works on microbial cell walls?

Answer 33

alternative pathway activators

Question 34

which complement activator is from IgG and IgM?

Answer 34

classical pathway activators

Question 35

which complement activator is adaptive immune response?

Answer 35

classical pathway activator

Question 36

which complement activator is innate immune response?

Answer 36

alternative pathway activator

Question 37

steps of classical pathway activators

Answer 37

1. Activated C1 cleaves C2 and C4, forming C4b2a 2. C4b2a is classical C3 convertase 3. C4b2a3b is classical C5 convertase 4. goes on to cleave C5 5. phagocytosis, activation of late complement, inflammation induction

Question 38

steps of alternative pathway activators

Answer 38

1. C3 cleaves sponatneously to C3a and C3b 2. C3b covalently binds to cell surface - if self it becomes C3bH (deactivated by factor I) - if microbe becomes C3bB (cleaved by factor D to become C3bBb) 3. goes on to cleave C5 4. phagocytosis activation of late complement, inflammation induction

Question 39

what is required for initiation of MAC?

Answer 39

C5b

Question 40

what forms a pipe that is critical to MAC?

Answer 40

Poly-C9 (5 C9's)

Question 41

what is the alternative pathway to C3 convertase within alternative pathway activators?

Answer 41

C3bBb