Question 1

Matching
For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it.
-High-affinity Ig receptor on mast cells important in immediate hypersensitivity reactions

Accepted Answer

FcɛRI is a high affinity IgE receptor expressed on mast cells and basophils Although serum IgE levels are relatively very low, FcɛR1 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.

Question 2

For each of the functions described in questions , select the complement system protein (A-F) that best matches it.
-This complement fragment is a component of the membrane attack complex.

Accepted Answer

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

Question 3

For each of the functions described in questions , select the complement system protein (A-F) that best matches it.
-Produced by C3 convertases, this opsonin promotes phagocytosis of microbes.

Accepted Answer

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.

Question 4

Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses?

Accepted Answer

The lumen of mucosal lined tissues, such as the intestinal and bronchial lumen, are protected by IgA, which is actively secreted at these sites
T cells do not normally migrate into these lumen and are usually involved in immune responses to organisms that breach the surface linings of these structures
The epithelial linings of mucosal tissues and the skin do contain lymphocytes that protect against invading pathogens
Both antibodies and T cells are involved in responses to infections within most other tissues.

Question 5

Matching
For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it.
-Low-affinity Ig receptor on natural killer cells that mediates antibody-dependent cell-mediated cytotoxicity

Accepted Answer

FcϒRIIIA(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.

Question 6

Matching
For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it.
-High-affinity Ig receptor on macrophages and neutrophils important for phagocytosis and activation

Accepted Answer

FcgRI (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.

Question 7

For each of the functions described in questions , select the complement system protein (A-F) that best matches it.
-This complement fragment is a chemoattractant for neutrophils.

Accepted Answer

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.

Question 8

For each of the functions described in questions , select the complement system protein (A-F) that best matches it.
-Generated by factor I-mediated proteolysis, this complement fragment binds to complement receptor 2 (CR2) on B cells and enhances B cell activation.

Accepted Answer

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.

Question 9

Matching
For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it.
-Ig receptor on B cells that mediates feedback inhibition

Accepted Answer

FcϒRIIB (CD32) is a low-affinity IgG receptor expressed on B lymphocytesWhen antigen-IgG complexes simultaneously bind to membrane Ig and to FcϒRIIB, phosphatases activated by FcϒRIIB block activating signals from the B cell antigen receptor complex.

Question 10

For each of the functions described in questions , select the complement system protein (A-F) that best matches it.
-Generated by factor I-mediated proteolysis, this opsonizing complement fragment binds to CR3 on phagocytes.

Accepted Answer

iC3b is covalently bound to cell surfaces and is produced by sequential factor I-mediated proteolytic processing of C3
iC3b binds to CR3 and CR4, which are integrins expressed by phagocytes.

Quiz 13: Effector Mechanisms of Humoral Immunity

Matching For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it. -High-affinity Ig receptor on mast cells important in immediate hypersensitivity reactions

For each of the functions described in questions , select the complement system protein (A-F) that best matches it. -This complement fragment is a component of the membrane attack complex.

For each of the functions described in questions , select the complement system protein (A-F) that best matches it. -Produced by C3 convertases, this opsonin promotes phagocytosis of microbes.

Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses?

Matching For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it. -Low-affinity Ig receptor on natural killer cells that mediates antibody-dependent cell-mediated cytotoxicity

Matching For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it. -High-affinity Ig receptor on macrophages and neutrophils important for phagocytosis and activation

For each of the functions described in questions , select the complement system protein (A-F) that best matches it. -This complement fragment is a chemoattractant for neutrophils.

For each of the functions described in questions , select the complement system protein (A-F) that best matches it. -Generated by factor I-mediated proteolysis, this complement fragment binds to complement receptor 2 (CR2) on B cells and enhances B cell activation.

Matching For each of the following descriptions in questions , select the Fc receptor (A-G) that best matches it. -Ig receptor on B cells that mediates feedback inhibition

For each of the functions described in questions , select the complement system protein (A-F) that best matches it. -Generated by factor I-mediated proteolysis, this opsonizing complement fragment binds to CR3 on phagocytes.