MCQ Immunology (86-100): Antibodies-II with Answers

Immunoglobulins, also known as antibodies, are glycoprotein molecules produced by effector B cells (plasma cells). By now, you might have accumulated vast knowledge about these antibodies, their structural differences, functional differences, unique features, and applications in diagnostics.

In this set of 10 MCQs about antibodies, you can find questions related to the different properties of antibodies. Take a copy and a pencil, and write down answers to each question as you proceed. At the end of this post, you will get an answer key with descriptions. Check your answer with the given answer keys and keep improving your understanding.

86. Which of the following antibody is an important host defense against encapsulated bacteria?
a. IgG1
b. IgG2
c. IgG3
d. IgG4

87. Which of the following immunoglobulin is the most abundant immunoglobulin in newborns?
a. IgA
b. IgM
c. IgG
d. IgD

88. Which of the following immunoglobulin is produced early in the primary response to infection?
a. IgE
b. IgA
c. IgG
d. IgM

89. Which of the following immunoglobulin is the primary host defense against parasitic infections?
a. Secretory IgA
b. IgG
c. IgM
d. IgE

90. Which of the following immunoglobulin has the highest avidity of the immunoglobulins?
a. IgA
b. IgM
c. IgE
d. IgG

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91. The order of percent of total immunoglobulin in serum is
a. IgM, IgA, IgG, IgD, IgE
b. IgG, IgA, IgM, IgE, IgD
c. IgG, IgA, IgM, IgE, IgD
d. IgG, IgA, IgM, IgD, IgE

92. Which of the following antibody is a prominent antigen receptor expressed on B Cells?
a. IgG
b. IgA
c. IgM
d. IgE

93. The antibody which is found in secretions is:
a. IgD
b. IgE
c. IgG
d. IgA

94. Which of the following antibodies directly participate in the opsonization process?
a. IgM
b. IgG
c. IgA
d. IgE

95. Complement fixation is one of the most crucial host defenses against infections. The complement is activated by;
a. IgM Only
b. IgG only
c. both IgM and IgG
d. all five classes of antibodies activate complements.  

96. Which type of antibody is MOST effective in activating complement?
A)     IgG1
B)      IgG2
C)      IgG3
D)     IgM

ANSWERS

86. b: IgG2
The IgG2-subclass deficiency is associated with a diminished immune response to (bacterial capsular) polysaccharide antigens.
87.c (IgG).
IgG can cross the placenta and establish passive immunity. Infants also get secretory IgA (SIgA) via breastfeeding.
88. d (IgM)
Immunoglobulin M (IgM) antibodies are produced as a body’s first response to a new infection. 
89. d (IgE)
IgE is involved in allergic reactions and immune responses to helminths and protozoan pathogens. 
90. b (IgM)
Avidity is a measure of the total binding strength. As IgM can exist as a pentameric form, it has the highest avidity.
91. d (IgG> IgA >IgM > IgD >IgE)
About 70-80% of the immunoglobulins in the blood are IgG and IgE is the least abundant immunoglobulin in the serum.
92. c (IgM).
Mature B cells have both immunoglobulin M (IgM) and IgD types of BCRs and IgM type BCRs are more common.
93. d (IgA)
Immunoglobulin A (IgA) often exists in a monomeric state when in the bloodstream but is secreted into the lumen of mucosal surfaces in a dimeric form. IgA can be found in saliva, tears, respiratory, gastrointestinal, and genitourinary secretions.
94. b (IgG)
Bacteria Opsonization occurs when immunoglobulin G (IgG) molecules bind to specific epitopes on bacterial surface antigens through the antigen-binding site, leaving the Fc region exposed. Phagocytes possess Fc gamma receptors and can bind to the Fc-coated bacteria and internalize them.
95. c (both IgM and IgG)

96. D (IgM)