Antibodies and Complements

Question 1

T/F. If antigen A is similar to antigen B, the body can distinguish between them and initiate separate immune responses.

Answer 1

True.

Question 2

What are some important features of antibodies?

Answer 2

Bind a variety of antigenic structures.
Exquisite discrimination of similar antigens.
Bind antigen with great strength.
Recognize antigen in its native form.

Question 3

The overall mission of antibodies is to neutralize the target ___.

Answer 3

antigen

Question 4

Which process uses antibodies to tag microbial organisms or infected cells for phagocytosis?

Answer 4

opsonization

Question 5

___ ___ is the recruit complement system to destroy microbial organisms or infected cells.

Answer 5

Complement Fixation

Question 6

___ ___ binds toxins in the blood and tissue to facilitate the removal of the toxins.

Answer 6

Direct neutralization

Question 7

T/F. Opsonization prevents bacterial adherence.

Answer 7

False, neutralization uses antibodies to prevent bacterial adherence. Opsonization has antibodies that promote phagocytosis.

Question 8

What is the major immunoglobulin in serum?

Answer 8

IgG (70-75% of all Igs)

Question 9

Which Ig represents the basic structure of all Igs?

Answer 9

IgG

Question 10

T/F. IgD provides neonatal immunity and plays a role in immunological memory.

Answer 10

False, IgG provides neonatal immunity and plays a role in immunological memory.

Question 11

IgD is less than ___% of circulating Igs, is a major component of ___ cell surface Ig, and is also called a ___-cell receptor.

Answer 11

1; B; B

Question 12

Which immunoglobulin is very scarce in serum and found on the surface of basophils and mast cells?

Answer 12

IgE

Question 13

___ is important for killing large parasites and contributes to an allergic reaction.

Answer 13

IgE

Question 14

___ mast cells have preformed granules containing ___ and other inflammatory mediators. Multivalent antigen ___ IgE antibody bound at the mast-cell surface, causing the release of granule contents.

Answer 14

Resting; histamine; crosslinks

Question 15

Which immunoglobulin is secreted into saliva?

Answer 15

IgA

Question 16

T/F. IgA is usually assembled as a dimer and its receptor binds it to the mucosal epithelium.

Answer 16

False, IgA is a dimer but its receptor transports it across the mucosal epithelium.

Question 17

Which immunoglobulin is a pentamer and makes up 10% of the total Igs?

Answer 17

IgM

Question 18

What two immunoglobulins can serve as B cell receptors?

Answer 18

IgD and IgM

Question 19

T/F. IgM is the first secreted Ab in response to the initial antigenic challenge.

Answer 19

True.

Question 20

What defense systems in the body does complement contribute to?

Answer 20

Control inflammatory reactions
Chemotaxis
Clearance of immune complexes
Cellular activation
Antimicrobial defense

Question 21

Which complement family member is a central component?

Answer 21

C3

Question 22

Which complement family members are late components?

Answer 22

C5
C6,C7, C8
C9

Question 23

Many complement components are ___. Their active sites are masked.
Activation occurs when the masking is removed mostly by ___ ___, resulting in the exposure of the active site.

Answer 23

proenzymes; proteolytic cleavage

Question 24

T/F. Fragments of complement molecules are the active complements.

Answer 24

True.

Question 25

What are the principle functions of the complement system?

Answer 25

opsonization and cell activation
chemotaxis
lysis of target cells

Question 26

Explain the process of opsonization and cell activation.

Answer 26

Complement fragments coat the surface of a target. Immune cells bind to coated target. Phagocytosis and cell activation.

Question 27

During chemotaxis, small ___ of complement form a ___ ___ that stimulates immune cells to move towards the site of infection.

Answer 27

fragments; concentration gradient

Question 28

Complement activation results in the assembly of ___ ___ ___. It insert itself into lipid bilayers and makes a large hole on the cell membrane to cause cell lysis.

Answer 28

membrane attack complex (MAC)

Question 29

The generation of active complement ___ leads to the expression of complement ___ (CR) on phagocytic cells.

Answer 29

fragments; receptors

Question 30

Microbial surface stimulate the activation of complements.
While ___ and ___ coat the surface of target, ___ and ___ induce chemotaxis. Recruited leukocytes kill the invading microbes.

Answer 30

C3b; C4b; C3a; C5a

Question 31

Binding of C3b to the microbe causes activation of ___ (a late component of complement). This leads to the formation of the ___ ___ ___, which causes lysis of the microbe.

Answer 31

C5b; membrane attack complex

Question 32

T/F. The classical pathway is similar to the innate immune response and the alternative pathway is similar to the adaptive immune response.

Answer 32

False, classical is adaptive because it is activated by an antibody-antigen complex containing IgM or IgG1-3.
The alternative pathway is innate because it is activated directly by microbial cell walls.

Question 33

What two pathways are activated by microbial surfaces?

Answer 33

lectin and alternative pathways

Question 34

What does the lectin pathway recognize?

Answer 34

terminal mannose groups

Question 35

___ (C3a/C3b) binds factor ___ (H/I) on self surface and is ___ (activated/deactivated) by factor ___ (H/I).

Answer 35

C3b; H; deactivated; I

Question 36

C3b is deactived by ___ in fluid.

Answer 36

hydrolysis

Question 37

C3b binds factor ___(B/D) on the surface of microbes and it becomes ___.

Answer 37

B; C3bB

Question 38

C3bB is cleaved by factor ___ (B/D) to generate C3bBb. C3bBb is the ___ pathway’s C3 ___.

Answer 38

D; alternative; convertase

Question 39

T/F. C3bBb catalyzes a significant amount of C3 cleavage.

Answer 39

True

Question 40

What is the adapter for the classical pathway?

Answer 40

C1

Question 41

what makes up the C1 complex?

Answer 41

C1q and C1r2s2

Question 42

T/F. Free antibody engages C1.

Answer 42

False, only antibody bound IgM or IgG to tissues activates C1 to generate C1qr2s2.

Question 43

Activated C1 cleave ___ and ___ to form C4b2a. C4b2a is the classical ___ ___. C4b2a3b is the classical ___ ___.

Answer 43

C2; C4; C3 convertase; C5 convertase

Question 44

Matching:

1. Phagocytosis of opsonized particles
2. Activation of late steps of complement
3. Inflammation induced by breakdown products

A. C5 convertase
B. C3b
C. C5a, C3a, C4a

Answer 44

1. B
2. A
3. C

Question 45

The late stage activation of complement forms the ___ ___ ___.

Answer 45

membrane attack complex.

Question 46

What is required to initiate MAC formation?

Answer 46

C5b

Question 47

T/F. C6, C7, C8, and multiple C9 form MAC.

Answer 47

False, C5b, C6, C7, C8, and multiple C9 form MAC.