Deck 7: Complement System

Question 1

Select the test that could be used to determine whether a patient has a specific deficiency in C3.

A) CH50
B) AH50
C) Radial immunodiffusion
D) Hemolytic titration assay

Answer 1

Radial immunodiffusion

Question 2

What is cleaved by C4b2a3b?

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

Answer 2

C5

Question 3

Which of the following has perforin-like activity?

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

Answer 3

C5b6789

Question 4

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

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

Question 5

C5b6789 functions in:

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

Question 6

Which complement receptor is involved in mediating phagocytosis?

A) CR1
B) CR2
C) CR3
D) CR4

Question 7

Which of the following can activate the alternative complement pathway?

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

Question 8

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 9

Chemotactic and anaphylactic factors are produced by proteolytic cleavage of:

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

Question 10

Which complement receptor is found on mature B cells?

A) CR1
B) CR2
C) CR3
D) CR4

Question 11

Which of the following complement components has chemotactic activity?

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

Question 12

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 13

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

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

Question 14

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.

Question 15

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

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

Question 16

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

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

Question 17

Which of the following acts as an opsonin?

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

Question 18

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 19

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

A) C1 esterase inhibitor.
B) membrane cofactor protein.
C) S protein
D) CD59.

Question 20

What is cleaved by C3bBb?

A) C3
B) C5
C) C6

Question 21

Lack of the complement inhibitor C1INH results in which disease?

A) Hereditary angioedema
B) Paroxysmal nocturnal hemoglobinuria
C) Immune complex disease
D) Meningitis

Question 22

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

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

Question 23

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 24

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

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

Question 25

Which factors are found in all three pathways?

A) Factors B and D
B) C4, C2, and C3
C) C5 through C9
D) C1qrs, C3, and C5

Question 26

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 27

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 28

Identify the condition that would result from a deficiency in complement component C2.

A) Increased vascular permeability
B) Hereditary angioedema
C) Severe infections with encapsulated bacteria
D) Immune complex disease

Question 29

Which of the following immunoglobulins is able to activate complement?

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

Question 30

Which factor is unique to the lectin pathway?

A) Factor B
B) C1q
C) Mannose-binding protein
D) Factor I

Question 31

Kidney glomeruli can become obstructed with immune complexes as a result of:

A) properdin deficiency.
B) inadequate C3b-mediated opsonization.
C) membrane attack complex formation.
D) autoantibodies that bind C3bBb.

Question 32

C4 binding protein (C4BP)acts in association with which factor to inactivate C4b?

A) Factor B
B) Factor D
C) Factor I
D) C1INH

Question 33

Which complement protein is the key intermediate in all pathways?

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

Question 34

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

A) Antibody
B) C3
C) Mannose
D) C1qrs

Question 35

The recognition unit in the classical complement pathway consists of:

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

Question 36

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

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

Question 37

Lack of the complement components C5 through C9 may result in which condition?

A) Neisseria infection
B) Paroxysmal nocturnal hemoglobinuria
C) Atherosclerosis
D) Meningitis

Question 38

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

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

Question 39

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 40

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

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

Question 41

Dense deposits of C3 breakdown products can accumulate in the kidneys because of:

A) properdin deficiency.
B) inadequate C3b-mediated opsonization.
C) membrane attack complex formation.
D) autoantibodies that bind C3bBb.

Question 42

Which of the following is referred to as C5 convertase?

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

Question 43

Identify the true statement about C3.

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

Question 44

What reagent is present in a CH50 assay and absent in an AH50 assay?

A) Calcium
B) Red blood cells
C) Ethylene glycol
D) Magnesium

Question 45

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

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

Question 46

Which of the following is an important function of the complement system?

A) Stimulation of growth of T cells
B) Decrease in vascular permeability
C) Clearance of antigen-antibody complexes
D) Increased production of antibody

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

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.

Question 49

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 50

A decreased CH50 and a decreased AH50 would indicate a low amount of which of the following complement components?

A) C4
B) C3
C) C4 binding protein
D) Factor B

Question 51

Which of the following represents C3 convertase?

A) C4b2a3b
B) C3bBbP
C) C1qrs
D) BbH

Question 52

Which statement about complement components is most accurate?

A) They 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 53

Identify the alternative pathway trigger.

A) Fungal cell walls
B) Mannose-binding protein
C) Antigen-MHC complexes
D) Antigen-antibody combination

Question 54

C5a promotes which of the following actions?

A) Phagocytosis of target cells
B) Inactivation of the alternative pathway
C) Increased vascular permeability
D) Beginning of the membrane attack unit

Question 55

Which factor helps to dissociate C3b from red blood cells?

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