Humoral Immunity

Question 1

humoral immunity components

Answer 1

• Th2 helper T-cells

- antigen-specific B-cell – plasma cells, memory cells

Question 2

B-cell receptor complex

Answer 2

• activate B-cells to become plasma cells
• antigen-recognition molecules
• accessory intracellular-signaling molecules

Question 3

3 signals required for B-cell activation

Answer 3

• antigen signal
• co-stimulatory signal
• cytokine signal

Question 4

B-cells are activated by ____

Answer 4

direct antigen signal

Question 5

B-cell activation results in ____

Answer 5

B-cell becoming plasma cell, class switch, proliferation, and antibody secretion

Question 6

antibodies are also called _____

Answer 6

immunoglobulins

Question 7

antibody general structure

Answer 7

• polypeptide chains
• antigen-binding fragment
• crystalline fragment

Question 8

there are ____ classes of antibodies that all have different ____

Answer 8

5;

functions

Question 9

4 structures of antibodies

Answer 9

• monomer
• dimer
• trimer
• pentamer

Question 10

activated B-cells can change the ____; new ___ determined by ___

Answer 10

class of the antibody;
class;
cytokine signals and type/amount of antigen

Question 11

in class switch, _____ change but ____ stays the same

Answer 11

constant regions of heavy chains (crystalline fragment);

antigen specificity

Question 12

it is possible to activate B-cells independent of T-cells, if there is a _____; example?

Answer 12

very big antigen signal;

lipopolysaccharide

Question 13

it is possible to activate B-cells independent of T-cells, and the result is ____ because _____

Answer 13

plasma cells that only produce IgM;
will not get a class switch due to absence of cytokine signal and co-stimulatory signal

Question 14

antibody functions: indirect

Answer 14

• complement activation
• opsonization
• ADCC (antibody dependent cell-mediated cytotoxicity)

Question 15

antibody functions: direct

Answer 15

• neutralization
• agglutination
• precipitation

Question 16

complement activation

Answer 16

classical pathway of complement pathway is dependent upon the presence of antibody-antigen complex to activate C1

Question 17

opsonization

Answer 17

some cells have crystalline fragment receptors – these cells look for and will bind to the crystalline fragment on the antibodies and that will act as an opsonin and initiate phagocytosis of any bacteria they’re attached to

Question 18

ADCC:

• used to ____
• activates ____
• requires ____

Answer 18

destroy large organisms, virus infected cells, and cancer cells;
NK cells, macrophages, or eosinophils;
prior antibody response

Question 19

neutralization of bacterial toxins

Answer 19

• antibodies produced against a toxin to remove it from solution and prevent it from interacting with a cell
• ex: tetanus vaccine

Question 20

neutralization of viruses

Answer 20

antibodies can directly interact with viruses and take them out of solution to prevent it from infecting a cell

Question 21

agglutination

Answer 21

IgM can cross-connect to multiple bacteria at once which can allow our antibodies to cause a clumping of bacteria and hold them in place so our immune cells can come in to attack and destroy bacteria

Question 22

precipitation

Answer 22

• if soluble antigens are being produced by bacteria, they can be directly attached by the antibodies and they can “pull them out of solution” (make them insoluble) so they accumulate
• precipitation prevents it from moving through the body and allows immune system to destroy and clear it out
• can also be useful in testing

Question 23

IgM

Answer 23

• largest of the immunoglobulins
• pentamer stabilized by a J-chain
• first antibody produced during the primary response to an antigen
• synthesized during fetal life

Question 24

IgG

Answer 24

• most abundant class
• transported across the placenta
• four classes: IgG1, IgG2, IgG3, IgG4

Question 25

IgA

Answer 25

• IgA1 molecules: predominantly in blood
• IgA2 molecules: predominantly in secretions
• dimers anchored by J-chain and secretory piece
• secretory piece may protect IgAs against enzyme degradation from bacteria

Question 26

secretory immune system

Answer 26

• lymphoid tissues throughout the body
• antibodies present in: tears, sweat, saliva, mucus, breast milk
• IgA is dominant Ig class

Question 27

IgE

Answer 27

• least concentrated Ig class in circulation
• binds to surface of mast cells and basophils
• defender against parasites
• mediator of many common allergic responses

Question 28

IgD

Answer 28

• low concentration in the blood
• primarily found on the surface of B lymphocytes
• function as one type of B-cell antigen receptor

Question 29

memory B-cells

Answer 29

doesn’t get activated all the way to plasma cell; in “arrested development” waiting for signal to initiate remainder of differentiation to become plasma cell

Question 30

memory T-cells

Answer 30

• effector activity declines with removal of antigen

- memory T-cells may remain for >20 years

Question 31

fetal and neonatal immunity

Answer 31

• antibody function is deficient

- passive immunity provided by maternal antibody (maternal IgG across placenta, secretory IgA in breast milk)

Question 32

aging and immune function

Answer 32

• decreased T-cell activity (thymus atrophy over lifespan)
• decrease in circulating memory B-cells
• decreased macrophage activity (increase in circulating antigen-antibody complexes)
• tolerance systems fail (increase in circulating auto-antibodies)