B Lymphocytes lecture
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Questions and Answers

What are B cells?

  • Cells responsible for blood clotting
  • A type of lymphocyte that produces antibodies (correct)
  • Cells that directly kill pathogens
  • A class of RBC

    • Where do B cells develop in birds and mammals?

  • In the thymus for both
  • In the bursa of fabricus in birds and bone marrow in mammals (correct)
  • In the spleen for both
  • In the lymph nodes for mammals and birds

    • Where do B cells become activated?

  • In the thymus
  • In the blood stream
  • In secondary lymphoid organs like lymph nodes or the spleen (correct)
  • In the bone marrow

    • How do B cells become activated?

    <p>Through antigen recognition by B cell receptors and co-stimulatory signals</p> Signup and view all the answers

    What is the co-stimulatory signal for B cell activation?

    <p>Binding of CD40 on B cells to CD40L</p> Signup and view all the answers

    How do B cells react to T-independent antigens or T-dependent antigens?

    <p>T-independent antigens directly activate B cells, T-dependent antigens require helper T cells</p> Signup and view all the answers

    What’s the main difference in B cell activation by T-dependent and T-independent antigens?

    <p>T-depending activation requires co-stimulation and produces stronger, longer lasting responses</p> Signup and view all the answers

    Why do B cells depend on T helper cells during T-dependent responses?

    <p>T helper cells produce cytokines and co-stimulators signals needed for activation</p> Signup and view all the answers

    Define the B cells’ primary immune response

    <p>The initial response with a lag phase, mainly producing IgM</p> Signup and view all the answers

    Define the B cells’ secondary immune response

    <p>A rapid, strong response characterized by memory cell activation and IgG production</p> Signup and view all the answers

    Compare the B cell secondary and primary immune response

    <p>The secondary response is faster, stronger and produces higher-affinity antibodies than the primary response</p> Signup and view all the answers

    Explain antibody diversity

    <p>Diversity arises from somatic recombination of V,D, and J gene segments in B cells</p> Signup and view all the answers

    What do you understand by B cell clonal selection?

    <p>Selection and proliferation of B cells specific to an antigen</p> Signup and view all the answers

    Following activation of B cells, what does the differentiation pathway look like?

    <p>Activated B cells differentiate into plasma and memory cells</p> Signup and view all the answers

    What’s the last stage of B cell differentiation?

    <p>Differentiation into plasma cells that secrete antibodies</p> Signup and view all the answers

    What happens in the germinal centers following B cell activation?

    <p>B cells undergo affinity maturation, isotope switching, and memory cell formation</p> Signup and view all the answers

    Which immunoglobulins are produced first in the primary response?

    <p>IgM</p> Signup and view all the answers

    What is B cell isotope switching?

    <p>Changing the antibody heavy chain constant region to produce different immunoglobulin classes</p> Signup and view all the answers

    What is B cell affinity maturation?

    <p>A selection of B cells producing antibodies with increased binding affinity due to somatic hypermutation</p> Signup and view all the answers

    What is the role of cytokines in B cell isotype switching?

    <p>They regulate isotype switching to immunoglobulin classes like IgG, IgA and IgE</p> Signup and view all the answers

    In which immune response, primary or secondary, are high-affinity antibodies produced?

    <p>Secondary immune response</p> Signup and view all the answers

    How do memory B cells develop?

    <p>Through activation in germinal centers during T-dependent responses</p> Signup and view all the answers

    What role do antibodies play in pathogen elimination?

    <p>Binding antigens to neutralize pathogens and mediate effector functions like phagocytosis and complement activation</p> Signup and view all the answers

    What’s the structure of an immunoglobulin molecule ?

    <p>A heterodimer with two heavy chains and two light chains linked by disulfide bonds</p> Signup and view all the answers

    Name the classes of immunoglobulins you know

    <p>IgM, IgA, IgG, IgE, IgD</p> Signup and view all the answers

    Which part of the immunoglobulin molecule is responsible for antigen binding?

    <p>The variable regions of the light and heavy chains (Fab)</p> Signup and view all the answers

    Which part of the immunoglobulin molecules is responsible for inducing ADCC by NK cells?

    <p>The Fc region</p> Signup and view all the answers

    Which immunoglobulin is responsible for protection of body surfaces?

    <p>IgA</p> Signup and view all the answers

    Which immunoglobulins can be found as receptors on B cells?

    <p>IgM and IgD</p> Signup and view all the answers

    What is the biological function of immunoglobulin D (IgD)

    <p>To serve as a receptor on naive B cells along IgM</p> Signup and view all the answers

    Which class of immunoglobulin is known for its role in allergic reactions?

    <p>IgE</p> Signup and view all the answers

    Which immunoglobulin is found in abundance in serum?

    <p>IgG</p> Signup and view all the answers

    What clinical samples are available for antibody detection?

    <p>Blood serum, saliva and tears</p> Signup and view all the answers

    Which immunoglobulin, in free form, is always found as a pentamer?

    <p>IgM</p> Signup and view all the answers

    What is the role of secretory component in secretory IgA?

    <p>To protect IgA from proteolytic enzymes and facilitate transport across mucosal epithelia</p> Signup and view all the answers

    Serum is a mixture of antibodies called ____?

    <p>Polyclonal antibodies</p> Signup and view all the answers

    What is the use of monoclonal antibodies in human and veterinary medicine?

    <p>Diagnosis of therapy of diseases, including cancer and autoimmune disorders</p> Signup and view all the answers

    What is immune tolerance?

    <p>The immune system’s ability to distinguish between self and non-self and avoid attacking self-tissues</p> Signup and view all the answers

    How do regulatory T cells participate in immune tolerance?

    <p>By suppressing the activation of immune cells that could react to self-antigens</p> Signup and view all the answers

    Where does central tolerance take place?

    <p>In the bone marrow and thymus</p> Signup and view all the answers

    Where does peripheral tolerance take place?

    <p>In secondary lymphoid organs and tissues throughout the body</p> Signup and view all the answers

    The development of B cells is divided into three stages, what are these three stages?

    <p>Maturation, activation and Differentiation</p> Signup and view all the answers

    Match to the appropriate description of the B cells stages

    <p>Maturation = Generation of mature immunocompetent B lymphocytes Activation = Contact of B lymphocytes with specific antigens Differentiation = Activated B cells become plasma cells that produce antibodies or become memory B cells Freebie = Freebie</p> Signup and view all the answers

    What type of T-independent antigens directly activate B cells by polyclonal activation?

    <p>TI-1 antigens</p> Signup and view all the answers

    Which receptors are TI-1 antigens recognized by for the activation of B cells?

    <p>BCR and TLR</p> Signup and view all the answers

    How do TI-2 antigens primarily activate B cells?

    <p>By cross-linking multiple membrane Ig receptors</p> Signup and view all the answers

    Which characteristic distinguishes TI-1 antigens from TI-2 antigens?

    <p>TI-1 antigens activate B cells non-specifically</p> Signup and view all the answers

    Which mechanism is NOT involved in the activation of B cells by TI-1 antigens?

    <p>Engagement of T cell help</p> Signup and view all the answers

    What role do the Igalpha and Igbeta chains play in B cell activation?

    <p>They transduce signals critical for B cell activation through their ITAM motifs.</p> Signup and view all the answers

    What factors influence the kinetics of a primary immune response?

    <p>Factors include the nature of the antigen, administration route, presence of adjuvants, and species of the individual.</p> Signup and view all the answers

    Why is the cytoplasmic tail of B cell receptors insufficient for signal transduction?

    <p>The BCR's short cytoplasmic tail is too short to transduce signals effectively on its own.</p> Signup and view all the answers

    How do ITAM motifs contribute to B cell signaling?

    <p>ITAM motifs in Igalpha and Igbeta chains become phosphorylated upon activation, initiating signaling cascades.</p> Signup and view all the answers

    What distinguishes the roles of antigens in T-independent versus T-dependent B cell activation?

    <p>T-independent antigens directly activate B cells, while T-dependent antigens require help from T helper cells.</p> Signup and view all the answers

    Math the definition to each of the events during lag time.

    <p>Clonal selection = Selection of B cells with specificity to foreign antigens Clonal expansion = Increase in number of antigen specific cells Differentiation = Development of plasma cells and memory cells Production of antibodies = Mostly IgM and IgG produced</p> Signup and view all the answers

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