Immunology: Humoral Immune Responses I

Question 1

Avidity

Answer 1

The sum total of the strength of binding of two molecules or cells to one another at multiple sites

Question 2

Affinity

Answer 2

Strength of binding of one site on a molecule to its ligand

Question 3

5 main heavy chain classes/isotopes

Answer 3

• IgM
• IgD
• IgA
• IgG
• IgE

Question 4

Most abundant and long-lived Ig in serum

Answer 4

IgG

Question 5

Antibody that penetrates extravascular body spaces

Answer 5

IgG

Question 6

First antibody to be produced in a humoral immune response

Answer 6

IgM

Question 7

Antibody that is most effective at activating complement

Answer 7

IgM

Question 8

Important in rapid control of bacterial infections

Answer 8

IgM

Question 9

Principle isotype in secretions

Answer 9

IgA

Question 10

Neutralizes bacterial toxins and viruses

Answer 10

IgG

Question 11

Opsonizes pathogens to enhance phagocytosis

Answer 11

IgG

Question 12

Sensitizes for killing by NK cells

Answer 12

IgG

Question 13

Activates classical complement pathway

Answer 13

IgG

Question 14

Antibody that crosses placenta to protect fetus

Answer 14

IgG

Question 15

Occurs in blood and extravascular sites as monomer

Answer 15

IgA

Question 16

Forms dimers with J chains

Answer 16

IgA

Question 17

Occurs as pentamers with J chains

Answer 17

IgM

Question 18

Act mainly as neutralizing antibody on epithelial surfaces

Answer 18

IgA

Question 19

Cell surface receptor involved in lymphocyte activation and suppression

Answer 19

IgD

Question 20

Coexpressed with IgM on surface of mature B cell

Answer 20

IgD

Question 21

Secreted in upper respiratory mucosa

Answer 21

IgD

Question 22

Is always a monomer

Answer 22

IgE

Question 23

Occurs in very low concentration in serum

Answer 23

IgE

Question 24

Binds with high affinity on mast cells

Answer 24

IgE

Question 25

Antigen binding of IgE to mast cells triggers

Answer 25

Degranulation and release of inflammatory mediators

Question 26

IgE binding to mast cells occurs during

Answer 26

Allergic reactions

Question 27

Important in host resistance to parasite infections

Answer 27

IgE

Question 28

Sensitizes for killing by eosinophils

Answer 28

IgE

Question 29

Class switching enables

Answer 29

The same assembled VH exon to be associated with different CH genes during an immune response

Question 30

Every B cell begins by expressing

Answer 30

IgM with a particular VH exon

Question 31

A mature B cell expresses both __ and ___ on its cell-surface

Answer 31

IgM and IgD

Question 32

Coexpression of IgM and IgD on B cell surface is regulated by

Answer 32

RNA processing or splicing

Question 33

Isotype switching

Answer 33

After exposure to antigen, assembled VH exon may be expressed in IgG, IgA, or IgE antibodies

Question 34

Molecular basis for isotype switching is

Answer 34

DNA rearrangement

Question 35

Istotype switching vs. VDJ joining

Answer 35

• Always productive
• Uses different enzymes (AID)
• Happens after antigen stimulation
• Is not random (regulated by external signals)

Question 36

Exposure of activated B cells to IL-4 induces

Answer 36

IgE production

Question 37

Exposure of activated B cells to TGF-beta induces

Answer 37

IgA production

Question 38

Immunoglobulins of all heavy chain isotypes can be produced either

Answer 38

• In secreted form OR

- As a membrane-bound receptor

Question 39

Transition from membrane to secreted heavy chain occurs at the level of

Answer 39

RNA processing