Immunology Review

Question 1

What are the important immunoglobulins in antibacterial defense?

Answer 1

IgA, IgM, and IgG

Question 2

What percentage of immunoglobulins is IgA?

Answer 2

5-15 %

Question 3

Where is IgA found?

Answer 3

on mucosal surfaces, in colostrum, respiratory and intestinal secretions, tears, saliva, and other secretions

Question 4

What is the half life of IgA?

Answer 4

6 days

Question 5

What is the function of IgA?

Answer 5

it can bind to fimbria to prevent adhesion of these bacteria to the mucosal surface and resists proteolytic digestion by intestinal enzymes

Question 6

What does IgA need help from to produce secretory IgA?

Answer 6

t-cell help

Question 7

How do bacteria stimulate the production of IgA?

Answer 7

they colonize or invade through mucosal surfaces

Question 8

What is the predominant immunoglobulin in the bloodstream and tissues?

Answer 8

IgG - 85% of the total

Question 9

What is the function of IgG?

Answer 9

opsonization and killing of bacteria, and chemotaxis

Question 10

What is opsonization and killing of bacteria mediated by?

Answer 10

complement

Question 11

How can IgG opsonize bacteria directly?

Answer 11

by facilitating bacterium-phagocytic contact via the Fc receptor on the phagocyte

Question 12

What response is IgG the principle antibody in?

Answer 12

the amnestic (booster) response

Question 13

What is required for the production of IgG?

Answer 13

T-cell help and generation of long term memory cells

Question 14

What species is IgG the predominant antibody on mucosal surfaces and in milk, colostrum, and intestinal tracts?

Answer 14

ruminants

Question 15

What is the primary antibody in the early immune response?

Answer 15

IgM

Question 16

Where is IgM found?

Answer 16

the intravascular space

Question 17

What is the function of IgM?

Answer 17

fixing complement

Question 18

In regards to pathogenic bacteria, what is IgM important for?

Answer 18

immunity against polysaccharide antigens on their surface

Question 19

What stimulates an IgM response (in regards to bacteria)?

Answer 19

bacterial polysaccharides and peptidoglycan because they are T-cell independent antigens

Question 20

What is the half-life for IgM?

Answer 20

5 days

Question 21

What percentage of immunoglobulins is IgE?

Answer 21

1%

Question 22

What is the half-life of IgE?

Answer 22

2.5 days

Question 23

Where is most IgE bound?

Answer 23

to Fc receptors on mast cells

Question 24

What happens when antigen binds to IgE?

Answer 24

the cell degranulates and releases histamine, prostaglandin, platelet activating factor, and cytokines

Question 25

What are the functions of complement?

Answer 25

opsonization and killing

Question 26

How does complement opsonize?

Answer 26

deposition of C3b onto the bacterial surface enhances the phagocytosis of the bacterium by interacting with receptors on the surface of the phagocyte

Question 27

How does complement kill?

Answer 27

the end-point of the complement cascade is the formation of the membrane attack complex (MAC) that is capable of lysing susceptible gram-negative bacteria.

Question 28

What pathways can complement act through?

Answer 28

classical or alternate

Question 29

Which pathway requires antibody?

Answer 29

classical

Question 30

What bacterial components are capable of activating the alternate pathway?

Answer 30

LPS, capsular polysaccharides, and other cell wall constituents

Question 31

What is lactoferrin?

Answer 31

an iron binding protein that is present in milk and many other secretions - its antibacterial effect derives from its ability to limit the amount of iron available for uptake by bacteria

Question 32

What is transferrin?

Answer 32

a protein that forms a similar function to lactoferrin but in serum

Question 33

What is conglutinin?

Answer 33

a component of bovine serum that can aggregate Ag-Ab complexes to which complement is bound

Question 34

What is fibronectin?

Answer 34

a serum protein with a number of binding sites for both bacteria and phagocytic cells; it helps to opsinize

Question 35

What must be intact in order for gram negative organisms to resist complement?

Answer 35

the complete outer membrane (LPS) and accomanying structures

Question 36

Which complement pathways can LPS activate?

Answer 36

classical and alternative

Question 37

Most bacteria associated with invasive infections are _______.

Answer 37

encapsulated

Question 38

What part of the outer membrane is associated with resistance to complement?

Answer 38

O-Antigen

Question 39

What does some bacteria produce that is capable of breaking down complement?

Answer 39

peptidases

Question 40

Are immunoglobulins alone harmless to most pathogenic bacteria?

Answer 40

yes

Question 41

What may inhibit the MAC of complement (generally)?

Answer 41

some proteins in the cell wall of bacteria

Question 42

How can bacteria degrade immunoglobulibs?

Answer 42

via trypsin-like enzymes

Question 43

How may bacteria avoid the immune response?

Answer 43

by infecting sites of the hosts body that have poor defenses (epithelial cells of the respiratory, alimentary, and urogenital tracts, the mammary gland, and the gall bladder)

Question 44

What is antigenic similarity?

Answer 44

when an organism possesses antigens that are similar to those of the host tissues

Question 45

What is antigenic shift?

Answer 45

when an organism alters the main component against which the host's immune response is directed