TEST BANK Cellular and Molecular Immunology 9th Edition Abbas

Cellular and Molecular Immunology 9th Edition
Abbas Test Bank

Abbas: Cellular and Molecular Immunology, 9th Edition
Antibodies and Antigens

Test Bank

Matching

Questions 1-5
Match each of the descriptions in questions 1-5 with the correct lettered antibody isotype
(A-E). (Answers may be used more than once.)
A. IgA
B. IgD
C. IgE
D. IgG
E. IgM

1. The secreted form of this isotype forms pentamers around a J chain

ANS: E. IgM is secreted as a J chain–linked pentamer.

2. The most abundant Ig isotype in the blood

ANS: D. The blood IgG conceN raR
ntU onIiN
tiS sGabToB
ut.3C.5Om
Mg/mL and includes four subtypes
(IgG1 to IgG4).

3. The isotype only found in membrane-bound form on naive B cells

ANS: B. Very little IgD is secreted, and in membrane form is only on the surface of naive
B cells. Its function is not well understood.

4. The isotype found predominantly in mucosal secretions
ANS: A. IgA accounts for almost two thirds of the 3 g of antibody produced each day by
an adult, most of which is produced in the gastrointestinal associated lymphoid tissues
and secreted into the gut lumen.

5. The isotype most closely associated with immediate hypersensitivity (allergic)
disease

ANS: C. Most IgE that is secreted is bound to mast cells, and it plays a role in the
activation of mast cells during allergic reactions.

Questions 6-10

Match each description in questions 6-10 with the appropriate lettered term (A-I).
A. Conformational determinant

,Test Bank 2


B. Linear determinant
C. Neoantigenic determinant
D. Hinge region
E. Immun complex
F. Fab
G. Fc
H. Tail piece
I. Hapten

6. A proteolytic fragment of an antibody molecule that contains an intact antigen-
binding site

ANS: F. Fab fragments, derived from enzymatic cleavage of Ig molecules, are composed
of one intact light chain covalently linked to the N-terminal region of one heavy chain
and include a single intact antigen-binding site.

7. A three-dimensional shape, formed by a portion of a macromolecule, to which an
antibody binds

ANS: A. Conformational determinants will usually be destroyed by physicochemical
disruption of macromolecules, such as by denaturation or proteolysis of proteins.

8. A small chemical group recognized by an antibody that is attached to a larger
macromolecule
ANS: I. Although haptens can be recognized by antibodies, they are not, by themselves,
able to stimulate an antibody response (i.e., they are not immunogens). Antibody
responses to haptens can be induced when the hapten is attached to a macromolecule,
called a carrier.

9. The proteolytic fragment of an antibody molecule that contains the heavy chain
constant region

ANS: G. The Fc fragment, generated by proteolytic cleavage of an antibody molecule, is
composed of the C-terminal end of the heavy chain and lacks the antigen-binding region.
This region of an intact Ig molecule, which can interact with Ig receptors and
complement, is called the Fc region.

10. A region of an antibody molecule that permits bivalent binding of antibodies to pairs
of surface epitopes varying in distance from one another

ANS: D. The hinge region, located between the two N-terminal Ig domains of the heavy
chains of most isotypes, is flexible, permitting variations in the distance between the two
antigen-binding sites.

,Abbas: Cellular and Molecular Immunology, 9th Edition

Effector Mechanisms of Humoral Immunity

Test Bank

Matching

Questions 1-4
For each of the following descriptions in questions 1-4, select the Fc receptor (A-G) that
best matches it.
A. FcRI (CD64)
B. FcRIIB (CD32)
C. FcRIIIA (CD16)
D. FcRI
E. FcRII (CD23)
F. FcR (CD89)
G. FcRn

1. High-affinity Ig receptor on mast cells important in immediate hypersensitivity
reactions

ANS: D. FcRI is a high affinity IgE receptor expressed on mast cells and basophils.
Although serum IgE levels are rNelU
atR elI
ivS yNvG yB
erT lo.
wC, FOcM
R1 receptors are fully occupied by
IgE due to the high affinity of the receptor. Cross-linking of this receptor by allergen
binding to the IgE leads to mast cell activation, which includes granule exocytosis with
release of mediators such as histamine, as well as production of lipid mediators and
cytokines.

2. High-affinity Ig receptor on macrophages and neutrophils important for phagocytosis
and activation

ANS: A. FcRI (CD64) is a high-affinity IgG1 and IgG3 receptor that mediates
phagocytosis of opsonized organisms and delivers signals that enhance microbicidal
activity of the phagocytes.

3. Low-affinity Ig receptor on natural killer cells that mediates antibody-dependent cell-
mediated cytotoxicity

ANS: C. FcRIIIA (CD16) is a low-affinity IgG receptor that targets natural killer (NK)
cells to bind and destroy IgG-opsonized target cells and signals the NK cell to release
cytotoxic granules.

4. Ig receptor on B cells that mediates feedback inhibition

ANS: B. FcRIIB (CD32) is a low-affinity IgG receptor expressed on B lymphocytes.
When antigen-IgG complexes simultaneously bind to membrane Ig and to FcRIIB,

, phosphatases activated by FcRIIB block activating signals from the B cell antigen
receptor complex.

Questions 5-9
For each of the functions described in questions 5-9, select the complement system
protein (A-F) that best matches it.
A. C3b
B. iC3b
C. C3d
D. C5b
E. C5a

5. Generated by factor I–mediated proteolysis, this complement fragment binds to
complement receptor 2 (CR2) on B cells and enhances B cell activation.

ANS: C. C3d is covalently bound to cell surface and is produced by sequential factor I–
mediated proteolytic processing of C3. It binds to CR2 on B cells simultaneously with
antigen binding to membrane Ig. CR2 is part of a coreceptor complex, which also
includes CD19 and CD21. CD19 transduces signals that synergize with the B cell
receptor complex signals to activate the B cell.

6. Generated by factor I–mediated proteolysis, this opsonizing complement fragment
binds to CR3 on phagocytes.

ANS: B. iC3b is covalently bouN dR
nU toScI l sG
elN urTfaBc.
esCaO
ndMis produced by sequential factor I-
mediated proteolytic processing of C3. iC3b binds to CR3 and CR4, which are integrins
expressed by phagocytes.

7. Produced by C3 convertases, this opsonin promotes phagocytosis of microbes.
ANS: A. C3b is the larger fragment of C3 convertase-mediated cleavage of C3, which
becomes covalently bound to cell surfaces and is recognized by complement receptor 1
(CR1) on phagocytes.

8. This complement fragment is a chemoattractant for neutrophils.

ANS: E. C5a is a small soluble fragment generated by C5 convertase-mediated cleavage
of C5. C5a binds to a G protein–coupled serpentine receptor on neutrophils and
stimulates chemokinesis. The C5a receptor is also expressed on other cell types, and C5a
has several proinflammatory functions, including mast cell and endothelial cell
activation. C3a and C4a have similar biologic activities as C5a, but they are not as potent.
Together, C5a, C4a, and C3a are called anaphylatoxins.

9. This complement fragment is a component of the membrane attack complex.
ANS: D. C5b is the larger fragment of C5 generated by C5 convertase. It is the initial
component in the formation of the membrane attack complex, which includes C5, C6,
C7, C8, and several C9s.

Multiple Choice