Deck 6: Complement System

Question 1

Which of the following is a characteristic of complement?

A) It is activated by IgE in the classical pathway.
B) It cannot be activated by molecules other than antigen-antibody complexes.
C) It plays a role in the lysis of target cells coated with specific antibodies.
D) It is enhanced by decay accelerating factor.

Answer 1

It plays a role in the lysis of target cells coated with specific antibodies.

Question 2

Which immunoglobulin(s)help(s)initiate the classic complement pathway?

A) IgA and IgD
B) IgM only
C) IgG and IgM
D) IgG only

Answer 2

IgG and IgM

Question 3

The target recognition molecule of the lectin pathway that initiates complement activation is:

A) C1q
B) C4
C) C5b6789
D) mannose-binding lectin

Answer 3

mannose-binding lectin

Question 4

Which complement component is found in both the classic and alternative pathways?

A) C1
B) C2
C) factor B
D) C3

Question 5

Which of the following is cleaved first by C1qrs in the classical pathway of complement activation?

A) C2
B) C3
C) C4
D) factor B

Question 6

C5b6789 functions in:

A) target cell lysis
B) recognition of antigen
C) chemotaxis
D) complement inhibition

Question 7

What is cleaved by C3bBb?

A) C3
B) C5
C) C6

Question 8

What is cleaved by C4b2a3b?

A) C3
B) C4
C) C5
D) C6

Question 9

The C5 convertase of the alternative pathway of complement activation is:

A) C4b
B) C4b2a
C) C4b2a3b
D) C3bBb3bP

Question 10

Which of the following complement components has chemotactic activity?

A) C3b
B) C3a
C) C1qrs
D) C5b6789

Question 11

Which of the following has perforin-like activity?

A) IgG
B) IFN-gamma
C) C5b6789
D) C3b

Question 12

The alternative and classical pathway C3 convertases are destabilized as a means of down-regulating complement function.One molecule that performs this function is:

A) C1 esterase inhibitor
B) membrane cofactor protein
C) complement receptors 1 and 2
D) CD59

Question 13

A native bacterial cell surface itself will activate complement via which pathway(s)?

A) classical
B) alternative
C) lectin
D) two of these
E) all of these

Question 14

Which of the following can activate the alternative complement pathway?

A) IgG
B) mannose-binding lectin
C) C3b
D) C1q

Question 15

Which of the following act as opsonins?

A) IgD
B) C3b
C) C5a
D) IL-2

Question 16

Which of the following is the correct order of activation of complement in the lectin activation pathway?

A) C1,C4,C2,C3
B) MBL,C4,C2,C3
C) C3,factor B,C3
D) MBL,C2,C3,C4

Question 17

Chemotactic and anaphylactic factors are produced by proteolytic cleavage of:

A) C1q,C1r,C1s
B) C4,C2
C) C5,C3
D) C5,C6,C7,C8

Question 18

The C3 convertase of the alternative pathway of complement activation is:

A) C3bBbP
B) C3bB
C) C4b2a3b
D) C4b2a

Question 19

The functions of C5a are to promote all of the following EXCEPT:

A) phagocytosis of target cells
B) contraction of smooth muscle
C) increased vascular permeability
D) leukocyte attraction to the site of inflammation

Question 20

Which of the following functions by inserting itself into target membranes and forming channels or holes in the membranes?

A) C3bBb3b
B) C4b2a
C) C5b6789
D) C3b

Question 21

Which factors are found in all three pathways?

A) factors B and D
B) C4,C2,C3
C) C5-C9
D) C1qrs,C3,C5

Question 22

In the alternate pathway,factor B must bind to which of the following to initiate the cascade?

A) factor I
B) C3b
C) C4b
D) properdin

Question 23

Which factor must be associated with factor H to inactivate complement components?

A) C1INH
B) factor I
C) DAF
D) CR1

Question 24

The recognition unit in the classical complement pathway consists of:

A) C4b2a3b
B) C5b6789
C) C1qrs
D) factor B

Question 25

Which factor is unique to the lectin pathway?

A) factor B
B) C1q
C) mannose-binding protein
D) factor I

Question 26

Which factors are only associated with the alternative pathway?

A) factor B and factor D
B) factor D and C3
C) factor B and C2
D) C2 and MBL

Question 27

A deficiency in complement component C2 would result in:

A) increased vascular permeability
B) hereditary angioedema
C) severe infections with encapsulated bacteria
D) immune complex disease

Question 28

In the alternative pathway,C3 and C5 convertase are stabilized by which of the following?

A) properdin
B) factor B
C) factor I
D) C4

Question 29

Which complement protein is the key intermediate in all pathways?

A) C4
B) C2
C) C3
D) C1

Question 30

Which of the following is able to activate complement?

A) IgA
B) IgD
C) IgE
D) IgM

Question 31

A patient has an abnormal alternative pathway activation pattern.Which of the following complement proteins should be assessed to further elucidate the problem?

A) C1
B) C2
C) C3
D) C4

Question 32

Lack of the complement components C5-C* may result in which disease?

A) hereditary angioedema
B) paroxysmal nocturnal hemoglobinuria
C) atherosclerosis
D) meningitis

Question 33

Binding of a lectin to a sugar found in bacteria and fungi occurs in which complement pathway?

A) alternative pathway
B) classical pathway
C) MBL pathway
D) all of the above

Question 34

Which of the following represents C3 convertase?

A) C4b2a
B) C3bBbP
C) C1qrs
D) A and B
E) A and C

Question 35

All of the following can trigger the alternative pathway EXCEPT:

A) fungal cell walls
B) bacterial cell walls
C) yeast
D) antibody

Question 36

Lack of the complement inhibitor C1INH results in which disease?

A) hereditary angioedema
B) paroxysmal nocturnal hemoglobinuria
C) immune complex disease
D) meningitis

Question 37

Which complement factor polymerizes to cause lysis of a foreign cell?

A) C5
B) C6
C) C8
D) C9

Question 38

The membrane attack unit of complement is represented by which of the following?

A) C2a4b3b
B) C1qrs
C) C3bBbP
D) C5b6789

Question 39

The lectin pathway is initiated by the presence of which of the following?

A) antibody
B) C3
C) mannose
D) C1qrs

Question 40

The C5 convertase of the classical pathway of complement activation is:

A) C3bBbP
B) C3bBb3bP
C) C4b2a3b
D) C4b2a

Question 41

C4BP acts in association with which factor to inactivate C4b?

A) factor B
B) factor D
C) factor I
D) C1INH

Question 42

Which is characteristic of complement components?

A) All are active enzymes.
B) They are synthesized only when antigen is present.
C) They play a major part in the inflammatory response.
D) They are mainly produced in lymphoid tissue.

Question 43

Formation of the membrane attack complex (C5b-C9)is stopped by which factor?

A) factor H
B) factor I
C) C1INH
D) S protein

Question 44

All of the following statements are true of C3 EXCEPT:

A) It is known as the recognition unit.
B) It plays a key role in all pathways.
C) It is the most abundant of the complement proteins.
D) Its major function is opsonization.

Question 45

Which protein inhibits the classical complement pathway at the very beginning of it?

A) C1INH
B) C4BP
C) C3BP
D) factor H

Question 46

Which of the following are important functions of the complement system?

A) lysis of foreign cells
B) increase in vascular permeability
C) clearance of antigen-antibody complexes
D) all of the above
E) all except one of the above

Question 47

Which of the following activities is associated only with the alternative pathway of complement fixation?

A) formation of a membrane attack unit
B) factor B and C3b combination
C) antigen-antibody combination
D) lysis

Question 48

Which factor helps to dissociate C3b from red blood cells?

A) factor B
B) DAF
C) C1INH
D) C5

Question 49

Which of the following is referred to as C5 convertase?

A) C4b2a
B) MASP1
C) C4b2a3b
D) C1qrs

Question 50

A system of serum proteins that interact to enhance the immune response by producing cytolytic,chemotactic,and other effects best describes:

A) complement
B) fibrinogen
C) haptoglobin
D) CRP