This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “B-Cell Development”.
1. After the development of B cells in bone marrow, they travel to which part of the human body?
a) Spleen
b) Liver
c) Lymph nodes
d) Pancreas
View Answer
Explanation: B cells develop in bone marrow and then continue to spleen for final maturation. This event is guided by sequential events leading to assembly, expression and signalling of the B-cell antigen receptor (BCR). As the B cells migrate to spleen, they pass through two transitional phases-T1 & T2. After the entry of B cells into the spleen, they are considered as T1 B cells. Within the spleen, T1 B cells transition to T2 B cells.
2. Who discovered B cells?
a) Edward Jenner
b) Max Cooper
c) Philippa Marrack
d) John Kappler
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Explanation: Max Cooper studied the development of B cells in 1960s. He found out that B cells are integral part of the adaptive immune system. He used experimental animal models, clinical evaluation of patients with immune deficiency diseases and the nascent technology of cell surface molecules of characterization. Further researches were made by Immunologists like Paul Ehrlich, Nossal and Lederberg.
3. Which cytokine is responsible for the development of B cell?
a) IL-7
b) IL-4
c) IL-5
d) IL-2
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Explanation: IL-7 is responsible for the development of B as well as T cells. IL-7 is a secreted cytokine as it is secreted by stromal cells and bound to IL-7R on the developing lymphocyte. Signals from this binding initiate cytoplasmic cascade which results in altered expression of proteins required for the development of B and T cells. In case of B cells, they develop in the bone marrow and migrate from outer part of the marrow.
4. Which human immunodeficiency results in failure to express the BTK gene?
a) Combined immunodeficiency disease
b) DiGeorge Syndrome
c) Wiskott-Aldrich Syndrome
d) Bruton’s agammaglobulinemia
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Explanation: Bruton’s agammaglobulinemia or X-linked agammaglobulinemia is an immunodeficiency disorder characterized by absence of mature B cells. This results in mutations in the BTK gene. This gene is present on the long arm of X chromosome and it plays an important role in the maturation of pro-B cells to pre-B cells. As a result, if mature B cells are absent in an individual, the BTK gene will not be expressed and hence it causes Bruton’s agammaglobulinemia.
5. B1 cells can produce low affinity antibodies than B2 cells.
a) True
b) False
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Explanation: During fetal life, bone marrow stem cells give rise to a B cell with some different properties designated as B1 B cells. These cells are self-renewing meaning they can produce more mature naïve cells like themselves in the peripheral lymphoid tissue but they can produce only limited number of Ig gene segments. As a result of this, B1 cells have low affinity to antibodies as they secrete only IgM and undergo very little somatic hypermutations.
6. Which continent is the origin for Burkitt Lymphoma?
a) Europe
b) Asia
c) Africa
d) South America
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Explanation: Burkitt Lymphoma was first identified in Africa in 1956. It is caused due to cancer in B cells. The cancer caused in B cell is of two types. It may be either indolent (slow-growing) or aggressive (fast-growing). Burkitt Lymphoma is recognised as aggressive (fast-growing) human tumour and often observed among young children of Africa. It is associated with impaired immunity and is fatal if not treated on time.
7. Which statement about Marginal Zone (MZ) B cell is NOT true?
a) MZ B cells are involved in T cell dependent cell responses
b) MZ B cells mainly home near the bone marrow
c) MZ B cells contribute towards T cell-dependent pathways
d) MZ B cells have better capability than follicular B cells
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Explanation: MZ B cells do not home near bone marrow. Their main site is near the marginal sinus of the spleen. This site is controlled and facilitated by the molecules SIP1 and SIP3 which are the receptors for sphingosine-1-phosphate. MZ B cells are mainly responsible for various T cell dependent actions and fight against blood-borne microbes. MZ B cells can also transport pathogens from the marginal sinus to the splenic follicles where follicular B cells reside.
8. Which one of the following is NOT the domain of the light chain of the fully functional antibody which plays an important role in recombination and gene rearrangement during B lymphocyte development?
a) Constant domain (C)
b) Variable domain (V)
c) Joining domain (J)
d) Diversity domain (D)
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Explanation: A fully functional antibody consists of two light and two heavy chains. Variable (V), joining (J) and constant (C) are the domains of the light chain whereas variable (V), joining (J), constant (C) along with diversity (D) are the domains of heavy chain. The genes encoding these domains of the light and heavy chains of the antibody get rearranged during the developmental process of B lymphocytes. When a specific group of genes encoding the various regions of antibody get expressed, it gives rise to huge repertoire of antibodies having infinite types of antigen specifies.
9. How many cell markers play an important role in maturation of B cell?
a) Three
b) Four
c) One
d) Two
View Answer
Explanation: Four cell markers play an important role in maturation of B cell. They are VCAM1, VLA4, SCF and c-kit molecules. VCAM and SCF are present on the stromal cells of the bone marrow while the other two are present on the Pro-B cells. The first interaction occurs between VCAM (stromal cells) and VLA4 (Pro-B cell). This interaction facilitates the interaction between SCF and c-kit molecules. These interactions signal the B cell to generate IL-7 receptor.
10. Which of the following is TRUE about immature B cells?
a) They follow the V-D-J recombination
b) They associate non-covalently with surface Ig
c) They help in clonal detection via BCR-mediated apoptosis
d) They induce few rounds of proliferation of B cells
View Answer
Explanation: Immature B cells have functional IgM and no other Ig expression. These cells have 3 fates if they become autoreactive. 1) Clonal detection via BCR-mediated apoptosis. 2) Reactivation of RAG to initiate process of light chain receptor. 3) Survive and escape the bone marrow but become anergic. On the other hand, V-D-J recombination, non-covalent association with surface Ig and induction of few rounds of B cell proliferation are mediated and carried out by Pre-B cells.
Sanfoundry Global Education & Learning Series – Immunology.
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