Test 2: Antibody and Effector B cell Functions

Question 1

What antibody do plasma cells produce in salivary glands?

Answer 1

IgA
(also lots of IgG)

Question 2

What are the functions of antibodies and Ig?

Answer 2

• neutralization of microbes and toxins
• opsonization and phagocytosis of microbes
• antibody-dependent cellular cytotoxicity
• lysis of microbes
• phagocytosis of microbes opsonized with complement fragments
• inflammation
• complement activation

Question 3

What is the role of the variable region in humoral immunity?

Answer 3

neutralization
- triggered by binding of antigens to variable regions

Question 4

What is the role of the constant region in humoral immunity?

Answer 4

elimination
- triggered by binding of antigens to variable regions

Question 5

For neutralization of microbes, what is binding molecules on the microbes required for?

Answer 5

infecting cells/tissue blocks colonization

Question 6

Which antibodies are the most effective?

Answer 6

antibodies with high affinity

Question 7

What clustering of FcR require?

Answer 7

recognition of multivalent antigen by Ig

Question 8

What’s the function of Fcy/RI/IIA?

Answer 8

promotes phagocytosis of Ig-coated microbes by phagocytes

Question 9

What’s the function of FcyRIIIA (CD16)?

Answer 9

induces killing of Ig-coated infected cells by NK cells
(cytotoxicity)

Question 10

What’s the function of FcERI?

Answer 10

induced degranulation of mast cells and basophils/eosinophils

Question 11

How does antibody-dependent cell mediated cytotoxicity work?

Answer 11

NK cells bind IgG-coated cells via FcyRIII (CD16)

Question 12

How does IgE and eosinophil-mediated killing of helminth work?

Answer 12

• FcERI binds FC portion of IgE-coated helminth
• triggers degranulation of toxic mediators that kill helminth
• does not target infected cells

Question 13

What is used for the classical complement pathway?

Answer 13

C4b2a–> C4b2aC3b
(lectin pathway follows)

Question 14

What is used for alternative complement pathway?

Answer 14

C3bBb–> C3bBbC3b

Question 15

What is the result of 3 major pathways of complement activation?

Answer 15

results in phagocytosis, inflammation, and destruction of microbes

Question 16

What are the early steps of the alternate complement pathway?

Answer 16

• triggered by binding of C3b to microbial surfaces

Question 17

What are the early steps of the classical complement pathway?

Answer 17

• triggered by binding of C1 to microbe-bound antibodies (IgG, IgM)

Question 18

What are the early steps of the lectin complement pathway?

Answer 18

• triggered by binding of circulating lectins (MBL) to microbe polysaccharides (mannose)

Question 19

What is the most important step of complement activation?

Answer 19

cleavage of C3 by C3 converts which results in the coating of microbes with C3b for opsonization

Question 20

What is the late step-membrane-attack complex?

Answer 20

• late step results in formation of membrane attack complex (MAC)
• MAC= C5b, C6, C7, C8 and multiple C9 that form a pore
• Neisseria susceptible due thin cell wall and allows pore to do damage

Question 21

What is the function of the complement system?

Answer 21

• opsonization of microbes by C3b induces their phagocytosis

Question 22

What is important for Neisseria infection?

Answer 22

MAC due to thin well and pore damage