T cells recognize antigen when the antigen ___________________.
forms a complex with membrane-bound MHC molecules on another host-derived cell.
is internalized by T cells via phagocytosis and subsequently binds to T-cell receptors in the endoplasmic reticulum
is presented on the surface of a B cell on membrane-bound immunoglobulins
bears epitopes derived from proteins, carbohydrates, and lipids
If viewing the three-dimensional structure of a T-cell receptor from the side, with the T-cell membrane at the bottom and the receptor pointing upwards, which of the following is inconsistent with experimental data?
The highly variable CDR loops are located across the top surface.
The membrane-proximal domains consist of Cα and Cβ.
The portion that makes physical contact with the ligand comprises Vβ and Cβ, the domains farthest
from the T-cell membrane.
The transmembrane regions span the plasma membrane of the T cell.
The cytoplasmic tails of the T-cell receptor α and β chains are very short
Unlike B cells, T cells do not engage in any of the following processes except _______________.
alternative splicing to produce a secreted form of the T-cell receptor
alternative splicing to produce different isoforms of the T-cell receptor
Unlike the C regions of immunoglobulin heavy-chain loci, the C regions of the T-cell receptor β-chain loci ______.
are functionally similar
do not contain D segments
are more numerous
are encoded on a different chromosome from the variable β-chain gene segments of the T-cell
do not encode a transmembrane region
possess non-templated P and N nucleotides
Which of the following statements regarding Omenn syndrome is incorrect?
A bright red, scaly rash is due to a chronic inflammatory condition.
Affected individuals are susceptible to infections with opportunistic pathogens.
It is invariably fatal unless the immune system is rendered competent through a bone marrow
It is the consequence of complete loss of RAG function.
There is a deficiency of functional B and T cells.
It is associated with missense mutations of RAG genes.
All of the following statements regarding γ:δ T cells are correct except ___________.
they are more abundant in tissue than in the circulation
the δ chain is the counterpart to the β chain in α:β T-cell receptors because it contains V, D, and J segments in the variable region
they share some properties with NK cells
activation is not always dependent on recognition of a peptide:MHC molecule complex
expression on the cell surface is not dependent on the CD3 complex
During T-cell receptor _____-gene rearrangement, two D segments may be used in the final rearranged gene sequence, thereby increasing overall variability of this chain.
The degradation of pathogen proteins into smaller fragments called peptides is a process commonly referred to as
The primary reason for transplant rejections is due to differences in _____ between donor and recipient.
T-cell receptor α chains
γ:δ T cells
When describing the various components of the vesicular system, which of the following is not included?
Which of the following is not a characteristic of immunoproteasomes?
They make up about 1% of cellular protein.
They consist of four rings of seven polypeptide subunits that exist in alternative forms.
They are produced in response to IFN-γ produced during innate immune responses.
They produce a higher proportion of peptides containing acidic amino acids at the carboxy terminus
compared with constitutive proteasomes.
They contain 20S proteasome-activation complexes on the caps.
Identify which of the following statements is true regarding the transporter associated with antigen processing (TAP).
TAP is a homodimer composed of two identical subunits.
TAP transports proteasome-derived peptides from the cytosol directly to the lumen of the Golgi
TAP is an ATP-dependent, membrane-bound transporter.
Peptides transported by TAP bind preferentially to MHC class II molecules.
TAP deficiency causes a type of bare lymphocytes syndrome resulting in severely depleted levels of
MHC class II molecules on the surface of antigen-presenting cells.
All of the following are included in the peptide-loading complex except _____________.
Which of the following best describes the function of tapasin?
Tapasin is an antagonist of HLA-DM and causes more significant increases in MHC class I than MHC
class II on the cell surface.
Tapasin is a lectin that binds to sugar residues on MHC class I molecules, T-cell receptors, and
immunoglobulins and retains them in the ER until their subunits have adopted the correct
Tapasin is a thiol-reductase that protects the disulfide bonds of MHC class I molecules.
Tapasin participates in peptide editing by trimming the amino terminus of peptides to ensure that
the fit between peptide and MHC class II molecules is appropriate.
Tapasin is a bridging protein that binds to both TAP and MHC class I molecules and facilitates the selection of peptides that bind tightly to MHC class I molecules.
Which of the following characteristics is common to both T-cell receptors and immunoglobulins?
Somatic recombination of V, D, and J segments is responsible for the diversity of antigen-binding sites.
Somatic hypermutation changes the affinity of antigen-binding sites and contributes to further diversification.
Class switching enables a change in effector function.
The antigen receptor is composed of two identical heavy chains and two identical light chains.
Carbohydrate, lipid, and protein antigens are recognized and stimulate a response.
The antigen-recognition site of T-cell receptors is formed by the association of which of the following domains?
Vα and Cα
Vα and Vβ
How many complementarity-determining regions contribute to the antigen-binding site in an intact T-cell receptor?
IgG possesses _______ binding sites for antigen, and the T-cell receptor possesses _______ binding sites for antigen:
In B cells, transport of immunoglobulin to the membrane is dependent on association with two invariant proteins, Igα and Igβ. Which of the following invariant proteins provide this function for the T-cell receptor in T cells?
All of the above
Which of the following is not a characteristic of native antigen recognized by T cells?
peptides ranging between 8 and 25 amino acids in length
not requiring degradation for recognition
amino acid sequences not found in host proteins
primary, and not secondary, structure of protein
binding to major histocompatibility complex molecules on the surface of antigen-presenting cells.
Which of the following statements regarding CD8 T cells is incorrect?
When activated, CD8 T cells in turn activate B cells.
CD8 is also known as the CD8 T-cell co-receptor.
CD8 binds to MHC molecules at a site distinct from that bound by the T-cell receptor.
CD8 T cells kill pathogen-infected cells by inducing apoptosis.
CD8 T cells are MHC class I-restricted.
Antigen processing involves the breakdown of protein antigens and the subsequent association of peptide fragments on the surface of antigen-presenting cells with ________________.
MHC class I or class II molecules
Which of the following statements regarding T-cell receptor recognition of antigen is correct?
α:β T-cell receptors recognize antigen only as a peptide bound to an MHC molecule.
αβ T-cell receptors recognize antigens in their native form.
α:β T-cell receptors, like B-cell immunoglobulins, can recognize carbohydrate, lipid, and protein
Antigen processing occurs in extracellular spaces.
Like α:β T cells, γ:δ T cells are also restricted to the recognition of antigens presented by MHC
Which of the following describes a ligand for an α:β T-cell receptor?
all of the above
none of the above
MHC class II molecules are made up of two chains called _______, whose function is to bind peptides and present them to _______ T cells.
alpha (α) and beta (β); CD4
alpha (α) and beta2-microglobulin (β2m); CD4
alpha (α) and beta (β); CD8
alpha (α) and beta2-microglobulin β2m); CD8
alpha (α) and beta (β); γ:δ T cells
The CDR3 loops of the T-cell receptor contact the _______.
side chains of amino acids in the middle of the peptide
co-receptors CD4 or CD8
membrane-proximal domains of the MHC molecule
constant regions of antibody molecules
α helices of the MHC molecule
MHC molecules have promiscuous binding specificity. This means that __________________.
a particular MHC molecule has the potential to bind to different peptides
when MHC molecules bind to peptides, they are degraded
peptides bind with low affinity to MHC molecules
none of the above describes promiscuous binding specificity
all of the above describes promiscuous binding specificity
T-cell receptors interact not only with peptide anchored in the peptide-binding groove of MHC molecules, but also with ____________________.
variable amino acid residues on α helices of the MHC molecule
Cross-priming of the immune response occurs when ______________________________.
viral antigens are presented by MHC class I molecules on the surface of a cell that is not actually infected by that particular virus, or peptides of nuclear or cytosolic proteins are presented by MHC class II molecules.
cytosol-derived peptides enter the endoplasmic reticulum and bind to MHC class II molecules
phagolysosome-derived peptides bind to MHC class II molecules
viral antigens are presented by MHC class II molecules on the surface of a cell that is not actually infected by that particular virus or peptides of nuclear or cytosolic proteins are presented by MHC class I molecules
phagolysosome-derived peptides bind to MHC class III molecules
In reference to the interaction between T-cell receptors and their corresponding ligands, which of the following statements is correct?
The organization of the T-cell receptor antigen-binding site is distinct from the antigen-binding site of immunoglobulins.
The orientation between T-cell receptors and MHC class I molecules is different from that of MHC class II molecules.
The CDR3 loops of the T-cell receptor α and β chains form the periphery of the binding site making contact with the α helices of the MHC molecule.
The most variable part of the T-cell receptor is composed of the CD3 loops of both the α and β
All of the above statements are correct.
The diversity of MHC class I and II genes is due to ___________________.
gene rearrangements similar to those observed in T-cell receptor genes
the existence of many similar genes encoding MHC molecules in the genome and extensive
polymorphism at many of the alleles
limited polymorphism at many of the alleles
The combination of all HLA class I and class II allotypes that an individual expresses is referred to as their ____________.
All of the following are oligomorphic except ___________________.
HLA-G α chain
HLA-DO β chain
HLA-DQ β chain
HLA-A α chain
HLA-DR α chain
All of the following are highly polymorphic except _____________.
HLA-A α chain
HLA-DO α chain
HLA-B α chain
HLA-DR β chain
HLA-C α chain
Of the following HLA α-chain loci, which one exhibits the highest degree of polymorphism?
Which of the following is/are not encoded on chromosome 6 in the HLA complex?
β2-microglobulin and invariant chain
HLA-G α chain
HLA-DR α chain
The _____ refers to the complete set of HLA alleles that a person possesses on a particular chromosome 6.
Peptides that bind to a particular MHC isoform usually have either the same or chemically similar amino acids at two to three key positions that hold the peptide tightly in the peptide-binding groove of the MHC molecule. These amino acids are called _____ and the combination of these key residues is known as its _________________.
anchor residues; peptide-binding motif
invariant chains; haplotypes
restriction residues; MHC allotype
Directional selection is best described as ______________________________.
all polymorphic alleles preserved in a population
T-cell receptor interaction with peptide:MHC complexes directed to a planar interface
a mechanism in T cells that is analogous to affinity maturation of immunoglobulins
selected alleles increase in frequency in a population
selection of most appropriate transplant donor directed at the identification of identical or similar
combinations of HLA alleles compared with the transplant recipient
The role of the CD3 proteins and ζ chain on the surface of the cell is to ___________________.
transduce signals to the interior of the T cell correct
bind to antigen associated with MHC molecules
bind to MHC molecules
bind to CD4 or CD8 molecules
facilitate antigen processing of antigens that bind to the surface of T cells
The immunological consequence of severe combined immunodeficiency disease (SCID) caused by a genetic defect in either RAG-1 or RAG-2 genes is _____________________.
lack of somatic recombination in T-cell receptor and immunoglobulin gene loci
lack of somatic recombination in T-cell receptor loci
lack of somatic recombination in immunoglobulin loci
lack of somatic hypermutation in T-cell receptor and immunoglobulin loci
lack of somatic hypermutation in T-cell receptor loci
Which of the following removes CLIP from MHC class II molecules?
CD8 T-cell subpopulations are specialized to combat _______ pathogens, whereas CD4 T-cell subpopulations are specialized to combat _______ pathogens.
Which of the following describes the sequence of events involved in processing of peptides that will be presented as antigen with MHC class I?
plasma membrane →TAP1/2 →proteasome →MHC class I →endoplasmic reticulum
TAP1/2 →proteasome →MHC class I →endoplasmic reticulum→plasma membrane
proteasome →TAP1/2 →MHC class I →endoplasmic reticulum →plasma membrane
proteasome →TAP1/2 →endoplasmic reticulum →MHC class I →plasma membrane
endoplasmic reticulum →proteasome →MHC class I →TAP1/2 →plasma membrane
One type of bare lymphocyte syndrome is caused by a genetic defect in MHC class II transactivator (CIITA), which results in the inability to synthesize MHC class II and display it on the cell surface. The consequence of this would be that ____________________________.
B cells are unable to develop
CD8 T cells cannot function
CD4 T cells cannot function
intracellular infections cannot be eradicated
peptides cannot be loaded onto MHC molecules in the lumen of the endoplasmic reticulum
Which of the following describes the sequence of events involved in the processing of peptides that will be presented as antigen with MHC class II?
protease activity →removal of CLIP from MHC class II →binding of peptide to MHC class II →endocytosis →plasma membrane
endocytosis →protease activity →removal of CLIP from MHC class II →binding of peptide to MHC class II →plasma membranecorrect
removal of CLIP from MHC class II →binding of peptide to MHC class II →protease activity →endocytosis →plasma membrane
binding of peptide to MHC class II →endocytosis →removal of CLIP from MHC class II →protease activity →plasma membrane
plasma membrane →endocytosis →protease activity →removal of CLIP from MHC class II →binding of peptide to MHC class II
Which of the following cell types does not express MHC class I?
Which of the following cell types is not considered a professional antigen-presenting cell?
all of the above are professional antigen-presenting cells
Which of the following is mismatched?
peptide-binding motif: combination of anchor residues in a peptide capable of binding a particular
MHC restriction: specificity of T-cell receptor for a particular peptide:MHC molecule complex
balancing selection: maintenance of variety of MHC isoforms in a population
directional selection: replacement of older MHC isoforms with newer variants
interallelic conversion: recombination between two different genes in the same family
Which is the most likely reason that HIV-infected people with heterozygous HLA loci have a delayed progression to AIDS compared with patients who are homozygous at one or more HLA loci?
The greater number of HLA alleles provides a wider variety of HLA molecules for presenting HIV- derived peptides to CD8 T cells even if HIV mutates during the course of infection.
Heterozygotes have more opportunity for interallelic conversion and can therefore express larger numbers of MHC alleles.
Directional selection mechanisms favor heterozygotes and provide selective advantage to pathogen exposure.
As heterozygosity increases, so does the concentration of alloantibodies in the serum, some of which cross-react with and neutralize HIV
Which of the following cell-surface markers differentiates hematopoietic stem cells from other cell constituents in the bone marrow?
membrane-bound stem-cell factor (SCF)
Which of the following is characteristic of a large pre-B cell?
VDJ is successfully rearranged and mu heavy chain is made.
V–J is rearranging at the light-chain locus.
mu heavy chain and lambda or kappa light chain is made.
V is rearranging to DJ at the heavy-chain locus.
D–J is rearranging at the heavy-chain locus
Which of the following statements is correct?
The κ light-chain genes rearrange before the heavy-chain genes.
The κ light-chain genes rearrange before the λ light-chain genes.
The λ light-chain genes rearrange before the heavy-chain genes.
he λ light-chain genes rearrange before the κ light-chain genes.
The μ heavy-chain genes rearrange first and then the λ light-chain genes rearrange