Chapter 9.2 quiz Flashcards
Which of the following is not a function of antibodies?
a. They neutralize pathogens by masking their surface
b. They act as molecular adaptors that bridge together pathogen and phagocyte surfaces
c. They exert toxic effects directly
d. They act as opsonins that mediate phagocytosis
e. They activate complement fixation
d. They act as opsonins that mediate phagocytosis
To mount the most effective antibody response that results in the synthesis of high-affinity antibodies, which of the following must occur?
a. recognition of thymus-independent (TI) antigens
b. isotype switching and affinity aturation
c. increased expression of TLR9 by B cells
d. somatic recombination
e. decreased expression of CD40 by B cells
b. isotype switching and affinity maturation
Immunoreceptor tyrosine-based activation motifs (ITAMs) are located on ____.
a the cytoplasmic tails of IgM
b. tyrosine kinases Blk, Fyn, nd Lyn
c. the cytoplasmic tails of Igalpha and Igbeta
d. breakdown products of C3b deposited on pathogen surfaces
e. thymus-independent antigens
c. the cytoplasmic tails of Igalpha and Igbeta
Identify the mismatched association.
a. Syk: Igbeta cytoplasmic tails
b. tyrosine kinase Lyn: CD81
c. B-cell co-receptor: CD21/CD19/CD81
d. C3b fragments: C3d and iC3b
e. hyper-IgM syndrome:CD40 ligand deficiency
b. tyrosine kinase Lyn: CD81
A primary focus of clonal expansion is best described as ____.
a. the location in the B-cell zone where conjugate pairs of B and T cells undergo cellular proliferation, isotype switching, and somatic hypermutation
b. the location in the medullary cords where conjugate pairs of B cells and T cells undergo cellular proliferation and IgM is secreted
c. the dark zone of the germinal center where centroblasts divide and pack closely together.
d. the initial wave of B-cell proliferation induced by T-independent antigens
b. the location in the medullary cords where conjugate pairs of B cells and T cells undergo cellular proliferation and Igm is secreted
A primary focus forms after a circulating naive B cells forms a conjugate pair with ___ in the ___ of the lymph node.
a. TH1 cell; B-cell zone
b. cytotoxic T cell; T-cell zone
c. follicular dendritic cell; germinal center
d. TFH; medullary cords
e. CD40 ligand; T-cell zone
d. TFH; medullary cords
B cells migrating directly from a primary focus to the medullary cords in a lymph node after activation with a T-dependent antigen differentiate into plasma cells that secrete predominantly ___.
a. IgD
b. IgE
c. sIgA
d. IgG
e. IgM
e. IgM
Lymphoblasts upregulate a transcription factor called ___ when they terminally differentiate into plasma cells.
a. NFkappa B
b. Bcl-xL
c. B-lymphocyte induced maturation protein 1 (BLIMP-1)
d. CD40
e. ICAM-1
c. B-lymphocyte induced maturation protein-1 (BLIMP-1)
The primary focus on B-cell expansion forms in the ___, whereas a secondary focus of B-cell expansion creates the ___.
a. T-cell area; medullary cords
b. medullary cords; T-cell area
c. T-cell area; B-cell area
d. medullary cords; germinal center
e. light zone; dark zone
d. medullary cords; germinal center
Proliferating centroblasts use the DNA-modifying enzyme activation-induced cytidine deaminase for ____.
a. cell proliferation
b. somatic hypermutation and isotype switching
c. apoptosis
d. upregulation of CD40
e. somatic recombination
b. somatic hypermutation and isotype switching
The main function of Bcl-xL is to ___ in the centrocyte.
a. provide death signals
b. induce somatic hypermutation
c. upregulate the expression of activation-induced cytidine deaminase
d. prevent apoptosis
e. induce isotype switching
d. prevent apoptosis
Engulfment of apoptotic centrocytes is facilitated by ___ in germinal centers.
a. follicular dendritic cells
b. immune-complex coated bodies (icosomes)
c. tingible body macrophages
d. antigen-specific B cells
e. antigen-specific TFH cells
c. tingible body macrophages
Which of the following is an accurate description of how centroblasts differ from centrocytes?
a. Centroblasts cease their expression of cell-surface immunoglobulins
b. Centroblasts divide more slowly than centrocytes
c. Centroblasts express CD44 but centrocytes do not
d. Centrocytes but not centroblasts initiate the process of isotype switching
e. Centroblasts participate in affinity matruation
a. Centroblasts cease their expression of cell-surface immunoglobulins
If a centrocyte does not interact with antigen and engage CD40 shortly after its derivation, then ___.
a. it recommences somatic hypermutation
b. it undergoes apoptosis
c. it moves back into the dark zone of the germinal center and switches its isotype
d. its surface immunoglobulin levels decreased and proliferation recommences
b. it undergoes apoptosis
____ is a mechanism that drives the preferential selection of immunoglobulins with the highest affinity for antigen.
a. Anergy
b. Isotype-switching
c. Affinity maturation
d. Antibody-dependent cell-mediated cytotoxicity
e. Transcytosis
c. Affinity maturation
___ in the switch regions positioned 5? to each heavy-chain C gene is induced by ___.
a. Somatic hypermutation; TI antigens
b. Chromatin remodeling; B-cell co-receptor signaling
c. recombination; survival signals received from follicular dendritic cells
d. Transcription; helper T-cell cytokines
e. Gene repression; apoptotic signals received from tingible body mactrophages
d. Transcription; helper T-cell cytokines
Plasma cells and memory B cells differentiate most immediately from ___.
a. centrocytes
b. centroblasts
c. B-1 cells
d. IgG-secreting B cells
e. Pre-B-cells
a. centrocytes
Which of the following statements is true regarding the complement component C4B?
a. Deficiency of C4B is associated with systemic lupus
b. C4B has similar properties to those of C4A
c. The thioester bond of C4B is preferentially acted upon by amino groups of macromolecules
d. C4B is encoded in the class II region of the MHC
e. The gene for C4B is duplicated or deleted in some individuals
e. The gene for C4B is duplicated or deleted in some individuals.
Which of the following is able to bind to C1q?
a. bacterial adhesins and toxoids
b. IgM and C-reactive protein
c. hemagglutinin
d. lipopolysaccharide
e. classical C3 convertase
b. IgM and C-reactive protein