Chapter 6

Question 1

Which of the following complement fixation pathways can be initiated by a soluble C3 convertase?

Answer 1

Alternative

Question 2

Which of the following provides serine protease activity in the classical complement activation pathway?

Answer 2

Both B and C

Question 3

Which of the following is the MOST potent anaphylatoxin produced during the complement cascade?

Answer 3

C5a

Question 4

To which of the following is MBL most structurally similar?

Answer 4

C1q

Question 5

Which of the following refers to the complex that provides the enzymatic activity in the alternative pathway C3 convertase?

Answer 5

C3̅b̅B̅b̅

Question 6

Which of the following is TRUE about the C5 convertase?

Answer 6

All of the above

Question 7

Which of the following BEST explains the timing of the classical pathway of complement fixation, relative to the other pathways of complement fixation, against a pathogen in an individual who has never been exposed to said pathogen?

Answer 7

No target for C1qrs exists on the surface of the pathogen in the earliest stages of the response to it.

Question 8

Which of the following binds to surface-bound C3b during formation of the alternative C3 convertase?

Answer 8

Factor B

Question 9

Which of the following can be directly activated as a soluble protein in the microenvironment surrounding a pathogenic cell?

Answer 9

C3

Question 10

Which of the following acts as a protease that is required to generate the alternative pathway C3 convertase?

Answer 10

Factor D

Question 11

Which of the following is the first complement factor to be activated, resulting in insertion of one of its subunits into the pathogen surface in two of the three complement fixation pathways?

Answer 11

C4

Question 12

Which of the following, when activated itself, acts as a protease that converts soluble C3 into C3a and C3b in the alternative pathway?

Answer 12

Factor B

Question 13

Which of the following, when activated, utilizes its “a” component instead of the “b” component in the formation of the C3 convertase?

Answer 13

C2

Question 14

Which of the following immunoglobulin isotypes is the MOST efficient at initiating a complement fixation cascade?

Answer 14

IgM

Question 15

Addition of which of the following components to any C3 convertase leads to the formation of the C5 convertase?

Answer 15

C3b

Question 16

Which form of IgM is MOST readily recognized by C1q?

Answer 16

“Staple-form” pentameric IgM

Question 17

Which of the following acts as a positive regulator of complement fixation via stabilization of C3bBb?

Answer 17

Properdin

Question 18

Which of the following acts as a serine protease that, with cofactors, cleaves C3b and C4b?

Answer 18

Factor I

Question 19

Which of the following facilitates dissociation of both the C4b2a and C3bBb C3 convertases?

Answer 19

DAF (CD55)

Question 20

Which of the following is capable of initiating the alternative pathway of complement fixation by directly binding to the surfaces of certain cell types?

Answer 20

Properdin

Question 21

The MAC consists of a multimeric complex of which of the following proteins that, by their association, forms a pore in the surface of the attacked cell?

Answer 21

C9

Question 22

How does binding of complement-opsonized microbes to CR1 facilitate clearing of the microbe from the host?

Answer 22

All of the above occur as a result of CR1 binding of complement-opsonized microbes.

Question 23

Which of the following is TRUE about the binding of C5b to the pathogen surface?

Answer 23

Both B and C

Question 24

Which of the following is NOT an effect of C3a and C5a binding their receptors on leukocytes?

Answer 24

All of the above are effects of C3a and C5a binding their receptors.

Question 25

Which of the following regulates complement function by directly inhibiting formation of the MAC?

Answer 25

Protectin (CD59)