Complement Flashcards
The classical complement pathway is activated by
a. most viruses.
b. antigen–antibody complexes.
c. fungal cell walls.
d. All of the above
b. antigen–antibody
All of the following are characteristic of complement components except
a. normally present in serum.
b. mainly synthesized in the liver.
c. present as active enzymes.
d. heat-labile.
c. present as active enzymes.
All of the following are true of the recognition unit except
a. it consists of C1q, C1r, and C1s.
b. the subunits require calcium for binding together.
c. binding occurs at the FC region of antibody molecules.
d. Clq becomes an active esterase.
d. Clq becomes an active esterase.
Which is referred to as C3 convertase?
a. C4b2a
b. C3bBb
c. iC3Bb
d. All of the above
d. All of the above
Mannose-binding protein in the lectin pathway is most similar to which classical pathway component?
a. C3
b. C1rs
c. C1q
d. C4
c. C1q
Which of the following describes the role of properdin in the alternative pathway?
a. Stabilization of C3/C5 convertase
b. Conversion of B to Bb
c. Inhibition of C3 convertase formation
d. Binding to the initiating antigen
Stabilization of C3/C5 convertase
Which best characterizes the membrane attack complex?
a. Each pathway utilizes different factors to form it.
b. C5 through C9 are not added in any particular order.
c. One MAC unit is sufficient to lyse any type of cell.
d. C9 polymerizes to form the transmembrane channel
d. C9 polymerizes to form the transmembrane channel
All of the following represent functions of the complement system except
a. decreased clearance of antigen–antibody complexes.
b. lysis of foreign cells.
c. increase in vascular permeability.
d. migration of neutrophils to the tissues
a. decreased clearance of antigen–antibody complexes.
Which of the following is true of the amplification loop in complement activation?
a. It is found in the alternative pathway.
b. iC3 binds factor B to generate amplification.
c. C3b is the product that is increased.
d. All of the above
d. All of the above
Factor H acts by competing with which of the following for the same binding site?
a. Factor B
b. Factor D
c. C3B
d. Factor I
a. Factor B
.A lack of CR1 receptors on red blood cells would result in which of the following?
a. Decreased binding of C3b to red blood cells
b. Lack of clearance of immune complexes by the spleen
c. Increased breakdown of C3b to C3d and C3dg
d. All of the above
b. Lack of clearance of immune complexes by the spleen
A lack of CR2 on cell membranes would result in which of the following?
a. Decrease in hemolysis
b. Increased susceptibility to infection
c. Decreased antibody production
d. Increase in antibody of the IgG class
c. Decreased antibody production
Why is complement not activated with anti-Rh (D) antibodies?
a. Rh antigens stimulate little antibody production.
b. Rh antigens are too far apart on red blood cells.
c. Rh antibodies are not capable of fixing complement.
d. DAF protects red blood cells from buildup of antibody
b. Rh antigens are too far apart on red blood cells.
The CH50 test measures which of the following?
a. The dilution of patient serum required to lyse 50 percent of a standard concentration of sensitized
sheep red blood cells
b. Functioning of both the classical and alternative pathways
c. Genetic deficiencies of any of the complement components
d. All of the above
d. All of the above
Which of the following would be most effective in preventing by stander lysis of red blood cells?
a. C1INH
b. Factor B
c. DAF
d. Factor H
c. DAF
