Notes

A defect in which of the following proteins blocks B-cell development at the pre-B-cell stage, resulting in almost no circulating antibodies in individuals with this defect?
a. IL-7 receptor
b. terminal deoxynucleotidyltransferase (TdT)
c. Pax-5
d. Bruton's tyrosine kinase (Btk)+
e. CD19.

What is the fate of an immature B cell that encounters and has specificity for self antigen?
a. If further heavy-chain and light-chain gene rearrangements are possible, it undergoes apoptosis.
b. Somatic hypermutation.
c. Decrease in production of IgD.
d. Continued rearrangement of heavy-chain genes.
e. Continued rearrangement of light-chain genes. +

_______ involves successive rearrangement at the light-chain loci when reactivity to self antigen occurs during B-cell development.
a. Receptor editing +
b. Somatic hypermutation
c. Chromosomal translocation
d. Clonal deletion
e. Anergy.

Which of the following is the first T-cell receptor complex containing the beta chain to reach the cell surface during the development of T lymphocytes?
a. gamma:beta:CD3
b. beta:CD3
c. alpha:beta:CD3
d. beta:CD44
e. pTalpha:beta:CD3. +

_______ of thymocytes is necessary to produce a T-cell repertoire capable of interacting with self-MHC molecules.
a. Positive selection+
b. Negative selection
c. Apoptosis
d. Receptor editing
e. Isotype switching.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is caused by a defect in
a. cathepsin L
b. a transcription factor called AIRE that regulates tissue-specific gene expression in the thymus +
c. the production of regulatory CD4 T cells
d. FoxP3
e. T-cell receptor gene rearrangement.

Which of the following is mismatched?
a. double-negative CD3- thymocytes: cortico-medullary junction +
b. double-negative CD3- thymocytes: subcapsular zone
c. double-positive CD3+ thymocytes: cortico-medullary junction
d. cortical epithelial cells: subcapsular regions
e. dendritic cells: cortico-medullary junction.

C3d and iC3b are breakdown products of _____ which binds to _____ of the B-cell co-receptor.
a. C3a; CR2
b. C3b; CR2+
c. C3c; CD81
d. C3c; CD19
e. C3b; CD19.

When bound to CR1, C3b is cleaved by _____, generating pathogen-associated B-cell co-receptor ligands.
a. factor I +
b. CR2
c. C3d
d. CD19
e. Lyn

Which of the following describes thymus-independent (TI)-2 antigens? (Select all that apply.)
a. They induce a late antibody response that is predominantly IgG.
b. They induce high-affinity antibodies through somatic hypermutation.
c. They induce long-term immunological memory.
d. They contain repetitive epitopes on the surface of microorganisms.+
e. None of the above

FcRn has which of the following characteristics? (Select all that apply.)
a. It binds to monomeric IgA in acidified endocytic vesicles.
b. It transports IgG out of the blood into tissue across the endothelium. +
c. It is similar in structure to an MHC class II molecule.
d. It protects IgA from degradation by plasma proteases.
e. None of the above

facilitation of antibody-dependent cell-mediated cytotoxicity in NK cells

____ a. poly-Ig receptor
____ b. Fc(gamma)RIII (CD16) +
____ c. Fc(epsilon)RI
____ d. FcRn
____ e. B-cell co-receptor
____ f. Fc(gamma)RII-B1 (CD32)

cross-linking of antibody:antigen complexes on mast cells, followed by degranulation

____ a. poly-Ig receptor
____ b. Fc(gamma)RIII (CD16)
____ c. Fc(epsilon)RI +
____ d. FcRn
____ e. B-cell co-receptor
____ f. Fc(gamma)RII-B1 (CD32)

binding to dimeric IgA and facilitation of its transcytosis
____ a. poly-Ig receptor +
____ b. Fc(gamma)RIII (CD16)
____ c. Fc(epsilon)RI
____ d. FcRn
____ e. B-cell co-receptor
____ f. Fc(gamma)RII-B1 (CD32).

inhibition of B-cell activation.

____ a. poly-Ig receptor
____ b. Fc(gamma)RIII (CD16)
____ c. Fc(epsilon)RI
____ d. FcRn
____ e. B-cell co-receptor
____ f. Fc(gamma)RII-B1 (CD32). +

The process involving receptor-mediated transport of macromolecules from one side of a cell to the other is called
a. phagocytosis
b. exocytosis
c. transcytosis +
d. signal transduction
e. opsonization.

IgM is particularly efficient at fixing complement because _____.
a. it is a much larger antibody than the other isotypes.
b. it has an extra CH domain.
c. it is made first in an immune response and therefore has first access to C1q.
d. it has five binding sites for C1q.+
e. it has easy access to extravascular areas

C3 convertase of the classical pathway is _____, whereas C3 convertase of the alternative pathway is _____.
a. C1a; C3bBb
b. C4bC2a; C3bBb +
c. C3bCR1; C3bBb
d. C4bC2a; C3bCR1
e. C1a; C3bCR1.

Complexes of IgG bound to soluble multivalent antigens can activate the classical pathway of complement, resulting in the deposition of _____ on the complex, targeting it for endocytic uptake by cells bearing _____.
a. C4b; CR2 and Fc receptors
b. C3b; CR2 and Toll-like receptors
c. C5-9; CR1 and Fc receptors
d. C3b; CR1 and Fc receptors+
e. C2a; CR2 and Toll-like receptors.

The gamma chain of the Fc(gamma)RI receptor is closely related to the _____, which contains _____.
a. FcRn; MHC class I-like structure
b. zeta chain of the T-cell receptor complex; ITAM motifs +
c. gamma chain of the Fc(gamma)RIII receptor; ITIM motifs
d. gamma chain of the Fc(alpha)RI receptor; ITIM motifs
e. gamma chain of the Fc(epsilon)RI receptor; ITIM motifs.

Antibody-dependent cell-mediated cytotoxicity (ADCC) is carried out by _____ after cross-linking of IgG1 or IgG3 antibodies on _____ receptors.
a. NK cells; Fc(gamma)RI
b. neutrophils; Fc(gamma)RI
c. NK cells; Fc(gamma)RIII +
d. macrophages; Fc(gamma)RIIB2
e. mast cells; Fc(epsilon)RI.

Which of the following polymerizes to form a transmembrane channel that
compromises the integrity of cell membranes?
a. C5
b. C6
c. C7
d. C8
e. C9+

Which of the following does not accurately describe complement components?
a. soluble proteins
b. made by the spleen +
c. located in extracellular spaces
d. some function as proteases once activated
e. activated by a cascade of enzymatic reactions.

The lectin pathway of complement activation is induced by:
a. C-reactive protein
b. antibodies bound to pathogens
c. mannose-binding lectin +
d. C3Bb
e. terminal components of the complement pathway.

Which of the following complement components is an opsonin that binds to
complement receptor 1 (CR1) on macrophages?
a. C3b +
b. C3a
c. Bb
d. Ba
e. C3bBb

The five isotypes of immunoglobulin differ from each other in their _____.
a. light-chain constant regions
b. heavy-chain constant regions +
c. light-chain variable regions
d. heavy-chain variable regions
e. heavy-chain variable and constant regions

A circulating B cell that has never before encountered antigen expresses _____ on the cell surface.
a. IgM and IgD+
b. IgM
c. IgD
d. IgM and IgG
e. IgG and IgE