Immunology midterm 3-4

10 The role of RAG-1 and RAG-2 enzymes is to Answers: a. cleave DNA at the junctions of RSSs and coding regions b. cleave proteins into peptides c. move peptides from the cytoplasm into the ER d. generate a hairpin structure and double-stand RNA break at the junctions of RSSs and coding regions e. signal lymphocytes to undergo apoptosis

A

12 In isotype switching, when the DNA of the H chains is rearranged, which of the following is true? Answers: a. the DNA in between the recombination sites is lost b. the DNA can go back to its germline formation c. the DNA in between the recombination sites is spliced to the leader sequence d. the spliced DNA is transcribed to RNA

A

19 The process by which a single B lymphocyte clone can switch from secreting IgM to IgE is called Answers: a. Isotype switching b. VDJ recombination c. RNA splicing d. Polyadenylatoin e. Allelic exclusion

A

22 The mechanism that does NOT generates antibody diversity PRIOR to interaction with antigen Answers: a. somatic hypermutation b. somatic recombination c. junctional modification d. N-nucleotide addition e. P-nucleotide addition

A

28 The peptide binding site of an MHC Class I molecule is made up of ___ Answers: a. alpha 1 and alpha 2 domains b. alpha 1 and beta 1 domains c. beta 1 and beta 2 domains d. alpha 2 and beta 2 domains

A

29 Beta-2microglobulin chain is a component of ____ Answers: a. MHC Class I b. MHC Class II c. T cell receptor d. B cell receptor e. CD3

A

34 Components of the MHC Class I antigen presentation pathway include Answers: a. beta-2 microglobulin b. invariant chain c. phagolysosomes d. HLA-DM e. beta-2 microglobulin and HLA-DM

A

37 ____ is removed so peptide can bind to MHC Class II molecules. Answers: a. CLIP (derived from the invariant chain) b. transporter associated with antigen processing (TAP) c. HLA-DO d. the proteasome e. B2-microglobulin

A

42 Viruses are able to stimulate cell mediated immunity because Answers: a. they can have antigens presented by MHC Class I molecules b. they replicate in the endocytic vesicles of cells and thus their antigens can be processed by proteasomes c. HLA-DM is specific for viral peptides d. they can have antigens presented by MHC Class III molecules e. they bind invariant chain

A

43 The differences in MHC molecules is achieved through ___ Answers: a. polygeny and multiple alleles b. somatic recombination of VDJ regions c. somatic hypermutation d. allelic exclusion e. addition of P- and N-nucleotides

A

46 Site of peptide loading of MHC Class II molecules Answers: a. endosomal/lysosomal compartments b. cytosol c. cell surface d. endoplasmic reticulum e. Golgi

A

53 Human MHC Class I includes ____ Answers: a. A, B, C b. DR, DQ, DP c. B, D d. A, B, D e. C, DR, B

A

54 Professional antigen presenting cells include ___ Answers: a. dendritic cells, B cells, macrophages b. dendritic cells, B cells, thymocytes c. dendritic cells, macrophages, NK cells d. macrophages, plasma cells, thymocytes e. NK cells, plasma cells, T cells

A

68 Which of the following is characteristic of a large pre-B cell? Answers: a. VDJ is successfully rearranged and mu heavy chain is made b. V-J is rearranging at the light-chain locus c. mu heavy chain and lambda or kappa light chain is made d. V is rearranging to DJ at the heavy-chain locus e. D-J is rearranging at the heavy-chain locus

A

71 The RAG-1 and RAG-2 recombinase Answers: a. operates in both T cells and B cells b. is produced in all cells, not just lymphocytes c. is involved in NK cell killing d. produces structural diversity in Class I MHC molecules e. produces structural diversity in Class II MHC molecules

A

72 The cellular marker(s) SPECIFICALLY identifies an early pro-B cell Answers: a. D-J rearrangement b. rearranged heavy chain; surrogate light chain on cell membrane c. CD34 positive, germ-line heavy and light chain immunoglobulin loci d. secretion of soluble immunoglobulin e. IgM and IgD on cell membrane

A

73 An important advantage of having two gene loci (kappa and lambda) for the light chain is that Answers: a. the likelihood of a successful rearrangement of light-chain genes increases b. immunoglobulins are heterogeneous in mature B cells being both kappa and lambda c. different effector functions are conferred by the two different light-chain loci d. either can associate with CD3 e. different functions are conferred by the two chains in T cells

A

78 Developing B cells that fail to make productive D to J heavy-chain rearrangements on both homologous chromosomes Answers: a. die by apoptosis in the bone marrow b. will rearrange heavy-chain loci multiple times until a productive rearrangement is made c. undergo clonal proliferation d. upregulate expression of transcription factors E2A and EBF e. turn on RAG-3 genes

A

8 Ig class switching refers to Answers: a. changing constant regions of heavy chains, leaving the same antigenic specificity b. joining V and D gene segments together c. joining V and J gene segments together d. joining V, D and J gene segments together e. switching a V gene segment for another V gene segment

A

1 A typical Ig molecule is composed of Answers: a. two light chains and one heavy chain b. two light chains and two heavy chains c. one light chain and one heavy chain d. two heavy chains only e. two light chains only

B

15 The five classes of Ig are Answers: a. IgA, IgB, IgC, IgD, IgE b. IgA, IgD, IgE, IgG, IgM c. IgA, IgB, IgD, IgF, IgM d. IgA, IgD, IgE, IgF, IgG e. IgA, IgG, Ig alpha, Ig beta, IgM, IgD, IgE

B

17 Which of the following BEST describes the differences between recombination of Ig heavy and light chain genes? Answers: a. Heavy chain genes rearrange DNA sequences, while light chain rearrangement is performed by RNA splicing b. Heavy chain genes encode V, D, and J segments that rearrange, while light chain rearrangement uses only V and J gene segments c. Heavy chain genes undergo rearrangement after light chain genes d. Heavy chain, but not light chain gene rearrangement uses mechanisms of junctional diversity e. Heavy chain genes are encoded on two different chromosomes, while light chain genes are encoded on one

B

23 In this preparations ALL immunoglobulin molecules are IDENTICAL Answers: a. IgG pooled from many donors b. IgG produced by a single plasma cell c. IgG isolated from a single person d. Fab fragments of IgG isolated from a single person e. Fc fragments of IgG isolated from a single person

B

36 Polymorphism of MHC molecules is concentrated in the____ Answers: a. area of the molecule that binds CD4 b. area of the molecule that binds to the antigenic peptide c. area within the beta-2 microglobulin d. transmembrane domain of the alpha chain e. cytoplasmic domain of both the alpha and beta chains

B

39 MHC molecules Answers: a. aid macrophages in ingesting bacteria b. present antigen to the TCR on T cells c. recognize antigen specifically d. break down antigen e. present antigenic peptides to the B cell receptor

B

41 Superantigens crosslink Answers: a. CD8 and CD4 domains on all MHC molecules b. MHC molecule with the T cell receptor c. MHC with the B cell receptors d. CD3 e. MHC peptide binding groooves

B

52 MHC Class I molecules are required for antigen recognition by Answers: a. B cells b. CD8+ T cells c. CD4+ T cells d. NK cells e. plasma cells

B

56 Antigen presentation is the process that lead to the display of Answers: a. the T cell receptor on alpha/beta T cells b. a peptide-MHC complex on the surface of an antigen presenting cell c. the B cell receptor on the surface of maturing B cells d. a peptide-MHC complex in the cytosol of dendritic cells e. inhibitory and activating receptors on NK cells

B

57 Human MHC Class II includes ____ Answers: a. A, B, C b. DR, DQ, DP c. B, D d. A, B, D e. A, DR, DP

B

58 The function of the MHC molecules is to Answers: a. aid macrophages in ingesting bacteria b. present antigen to the TCR on T cells c. recognize antigen specifically d. break down antigen e. present antigen to the B cell receptor

B

63 Antigen receptors of T lymphocytes contain only a single Answers: a. polypeptide chain b. site for antigen binding c. hypervariable region d. constant domain e. variable domain

B

66 Allelic exclusion ensures that Answers: a. only one MHC molecules is expressed on each T lymphocyte clone b. only one Ig specificity is expressed on each B lymphocyte clone c. only one MHC Class II molecule is expressed on each antigen presenting cell d. only one MHC Class I molecule is expressed on each antigen presenting cell e. only the Ig aloha and Ig beta signal molecules are expressed on B cells

B

67 The phenomenon in which further Ig rearrangement is shut down on the other chromosomal allele is called Answers: a. clonal selection b. allelic exclusion c. isotype switching d. productive rearrangement e. negative selection

B

76 If a pre-B cell fails to productively rearrange the heavy chain genes on both chromosomes, the result is Answers: a. the light chains will then attempt to rearrange b. the cell will undergo apoptosis c. the cell will begin to divide d. the cell will become an NK cell e. the cell reverts back to a lymophoid-lineage stem cell

B

9 Junctional diversity Answers: a. Stimulates somatic hypermutation after class switching b. Results from addition and subtraction of nucleotides from the cut ends of VDJ segments c. Results in altered amino acid sequences only in th hinge region of the heavy chain d. Activates alternative splicing of gamma and mu heavy chain transcripts e. Results from somatic hypermutation

B

77 Which of these are found on mature B cells? Answers: CD3 both IgD and IgG both IgD and IgM both CD4 and CD8 both IgA and IgE

B (both IgD and IgM)

13 Which is NOT a function of secreted antibody? Answers: a. Opsonization b. Blocking the binding of virus to cells c. Activation of CD4 T helper cells d. Activation of complement e. Protection of mucosal surfaces

C

14 The antigen receptor of T cells lacks Answers: a. Constant regions b. Variable regions c. Hinge regions d. Complementarity-determining regions e. Framework regions

C

18 Molecule expressed on mature B cells Answers: a. CD3 b. IgD and IgG c. IgD and IgM d. CD4 and CD8 e. CD3 and IgD and IgM

C

2 V/D and D/J splice junctions will be found in DNA which encodes Answers: a. Leader peptide b. Framework regions of the variable domains c. Complementarity-determining regions (CDRs) d. Hinge region e. Constant domains

C

20 Which statement is true concerning the generation of diversity at the Ig heavy chain locus? Answers: a. Somatic hypermutation occurs before a B cell is exposed to antigen b. Isotype switching occurs before a B cell is exposed to antigen c. P- and N-nucleotides are added to D-J gene junctions before a B cell is exposed to antigen d. M- and E-nucleotides are added to A-B gene junctions before a B cell is exposed to antigen e. Somatic hypermutation does not occur in B cells, only in T cells

C

24 The antigen specificity of a particular B cell Answers: a. is induced by interaction with MHC molecules b. is determined only by the L-chain sequence c. is determined by H-chain and L-chain variable region sequences d. changes after isotype switching e. is determined by the H-chain constant region

C

27 The CD3 complex Answers: a. relays a signal to the interior of the B cell b. associates with the Ig alpha and Ig beta chains c. associates with the T cell receptor d. relays a signal to the interior of an APC e. associates PRRs

C

31 Polygeny refers to Answers: a. the presence of multiple genes for the TCR b. the presence of multiple genes for the B cell receptor c. the presence of multiple genes for MHC Class I and MHC Class II molecules d. the presence of multiple alleles for MHC Class I and MHC Class II molecules e. the degenerate binding of peptide to the TCR

C

32 Molecule responsible for presenting viral antigen from infected cell Answers: a. CD4 b. CD8 c. MHC Class I d. MHC Class II e. MHC Class III

C

35 Peptides are transported from the cytosl to the lumen of the endoplasmic reticulum by Answers: a. the invariant chain b. the proteasome c. TAP1 and TAP2 heterodimer d. chaperone proteins e. beta-2-microglobulin

C

4 Allelic exclusion during Ig expression refers to Answers: a. deletion of B cells that recognize self antigens b. rearrangement of only V and D gene segments excluding the J segment c. expression of rearranged gene fragments from only one of the two homologous chromosomes d. expression of rearranged gene fragments from both homologous chromosomes e. deletion of IgM on B cell surface so only IgD is expressed

C

40 Peptide loading of MHC Class I molecules occurs ___ Answers: a. in the cytosol b. on the cell surface c. in the endoplasmic reticulum d. on the proteasome e. in a lysosome

C

44 Which set of MHC molecules are on the surface of a DENDRITIC CELL isolated from the lymph node of a human? Answers: a. HLA-A, HLA-B, HLA-C b. HLA-DP, HLA-DQ, HLA-DR c. HLA-A, HLA-B, HLA-C, HLA-DP, HLA-DQ, HLA-DR d. H-2-A, H-2-B, H-2-C, H-2-DP, H-2-DQ, H-2-DR e. ABC-A, ABC-B, ABC-C, ABC-D

C

47 Invariant chain (Ii) Answers: a. provide signal transduction in T cells b. activates B cells c. prevents binding of peptide to MHC Class II in the endoplasmic reticulum d. prevents binding of peptide to MHC Class I in the endoplasmic reticulum e. down regulates MHC molecules

C

48 Peptides are pumped into the endoplasmic reticulum with the help of the Answers: a. invariant chain b. proteasome c. transporter associated with antigen processing (TAP) d. MHC Class II molecules e. NOD

C

49 MHC Class II molecules are found on Answers: a. Endothelial cells of high endothelial venules b. Erythrocytes and platelets c. Professional Antigen presenting cells d. Cytolytic CD8+ T cells e. NK cells

C

50 MHC Class II molecules are found only on Answers: a. endothelial cells of high endothelial venules b. erythrocytes and platelets c. antigen presenting cells d. cytotoxic CD8+ T cells e. NK cells

C

55 ____ antigens are processed for presentation by MHC molecules Answers: a. polysaccharides b. nucleic acids c. proteins d. glycolipids e. carbohydrates

C

59 The human MHC complex is referred to as the Answers: a. H-2 complex b. B complex c. HLA complex d. ABC complex e. ABD complex

C

61 The human MHC complex is referred to as the Answers: a. H-2 complex b. B complex c. HLA complex d. ABC complex e. ABD complex

C

64 Which of the following T cells would survive the process of negative selection? Answers: a. those bearing a TCR specific for self MHC presenting self antigen b. those bearing a TCR specific for foreign MHC presenting non-self antigen c. those bearing a TCR specific for self MHC presenting non-self antigen d. those bearing a TCR specific for foreign MHC presenting self antigen e. all T cells survive negative selection

C

65 Unlike the surface immunoglobulins of B cells, the antigen receptors of T cells lack Answers: a. variable regions b. constant regions c. hinge regions d. complementarity-determining regions (CDRs) e. framework regions

C

69 The cellular marker(s) SPECIFICALLY identifies a stem cell Answers: a. D-J rearrangement b. rearranged heavy chain; surrogate light chain on cell membrane c. CD34 positive, germ-line heavy and light chain immunoglobulin loci d. secretion of soluble immunoglobulin e. IgM and IgD on cell membrane

C

75 During B cell development, the pre-B cells can be found in Answers: a. the liver b. the spleen c. the bone marrow d. the thymus e. in the peripheral tissue at the sight of infection

C

80 The series of stages a thymocyte goes through in thymus are in the order Answers: a. proliferation and differentiation to double-positive CD3 positive thymocyte, negative selection, positive selection, entry to the circulation b. negative selection, positive selection, expression of double-positive CD3 positive thymocyte, entry into circulation c. proliferation and differentiation to double-positive CD3 positive thymocyte, positive selection, negative selection, entry to the circulation d. positive selection, negative selection, loss of both CD4 and CD8, entry into circulation e. none, since thymocytes generate their TCRs in secondary lymphoid tissue

C

81 Pro-B cells produce a surrogate light chain composed of Answers: a. E2A and EFB b. Ig alpha and Ig beta c. VpreB and lambda5 d. RAG-1 and RAG-2 e. Pax5 and CD19

C

11 The mechanisms that does NOT contribute to the generation of diversity of B-cell antigen receptors Answers: a. Multiple V genes in the germ line b. Random assortment of L and H chains c. Imprecise recombination of V and J or V, D, and J segments d. Inheritance of multiple C-region genes e. Somatic hypermutation

D

21 Which mechanism does NOT contribute to the diversity of the Ig repertoire? Answers: a. somatic recombination b. somatic hypermutation c. removal and addition of nucleotides d. apoptosis e. removal of nucleotides

D

25 The ligand bound by the alpha/beta TCR CD4 T cell is a peptide derived from the antigen and bound to the Answers: a. alpha/beta chains of MHC Class III b. CD3 molecule c. MHC Class I molecule d. MHC Class II molecule e. peptide-binding groove of another T cell receptor

D

30 Products of TAP-1 and TAP-2 genes Answers: a. transport beta 2-microglobulin into the Golgi b. transport MHC molecules to the cell surface c. transport proteins through the proteasome d. transport peptides into the endoplasmic reticulum for binding to MHC class I e. transport peptides into the endoplasmic reticulum for binding to MHC class II

D

33 Molecule responsible for presenting extracellular antigen Answers: a. CD4 b. CD8 c. MHC Class I d. MHC Class II e. MHC Class III

D

38 An individual's haplotype identifies the ___ Answers: a. TCR repertoire inherited b. ABO blood group classification c. antibody repertoire inherited d. different HLA alleles inherited e. the inherited BCRs

D

5 Both the B cell receptor and T cell receptor Answers: a. recognizes membrane-bound antigen b. associates with the CD3 complex for signaling c. have one antigen binding site located in the variable region d. have three CDRs per chain e. have a constant region

D

51 Molecule that presents extracellular antigen Answers: a. CD4 b. CD8 c. MHC Class I d. MHC class II e. MHC class III

D

6 The heavy chain variable region of all classes/subclasses of Ig are encoded by Answers: a. V and C gene segments b. V and J gene segments c. V gene segments only d. V, D and J gene segments e. the Fc region

D

62 Cell-surface glycoproteins characteristic of stem cells, but stops being expressed when a cell has committed to the T-cell developmental pathway Answers: a. CD2 b. CD3 c. CD25 d. CD34 e. MHC class II

D

70 This cellular marker(s) SPECIFICALLY identifies a mature B cell Answers: a. rearranged heavy chain; surrogate light chain on cell membrane b. CD34 positive, germ-line heavy and light chain immunoglobulin loci c. secretion of soluble immunoglobulin d. IgM and IgD on cell membrane e. IgM only on cell membrane

D

16 Somatic recombination is NOT used for Answers: a. Development of a unique V domains for the light chain of immunoglobulins b. Development of a unique V domain for the heavy chain of immunolglobulin c. Isotype switching from IgM to IgG or IgA or IgE d. Development of a unique V domains for the T cell receptor e. Development of MHC diversity

E

26 The following is NOT true about T cell receptors Answers: a. most of them bind antigen bound to MHC molecules b. may be made up of alpha and beta chains c. may be made up of gamma and delta chains d. contain variable regions e. bind soluble antigen

E

3 Complementarity determining regions (CDRs) function in Answers: a. alleleic exclusion b. activation of lymphocytes c. activation of complement d. binding of Fc receptors e. binding antigen

E

45 Select the false statement about Th cells Answers: a. Th2 cells activate B cells displaying antigen-derived peptides on MHC Class II molecules b. Th1 cells activate macrophages that are displaying pathogen peptides on MHC Class II molecules c. Th cells express a glycoprotein called CD4 d. Th cells can differentiate into Th1 and Th2 cells e. Th cells lack expression of CD3

E

7 The basic monomer structure of an Ig molecule is made up of Answers: a. heavy chain and beta-2 microglogulin b. light chains and hinge region c. hinge region and heavy chain d. heavy chains (2) and hinge region e. heavy chains (2), light chains (2), and hinge region

E

74 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? Answers: a. gamma/beta:CD3 b. beta:CD3 c. alpha/beta:CD3 d. beta:CD44 e. pTalpha/beta:CD3

E

79 The earliest stages of B cell differentiation Answers: a. occur in the embryonic thymus b. require the presence of antigen c. involve rearrangement of kappa-chain gene segments d. involve rearrangement of the surrogate light-chain gene segments e. involves rearrangement of the heavy-chain gene segments

E

60 Molecule presents viral antigen from infected cell Answers: CD4 CD8 MHC class I MHC class II MHC class III

c MHC class I