Hematopoiesis and T Lymphocyte Development
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Questions and Answers

What are the three stages of hematopoiesis?

  • Thymus, Spleen, Yolk sac
  • Yolk sac, Liver, Bone marrow (correct)
  • Bone marrow, Lymph nodes, Thymus
  • Liver, Spleen, Bone marrow

    • Which type of T lymphocytes are the most numerous?

  • T-Suppressor Cells
  • T-Helper Cells (correct)
  • T-Cytotoxic Cells
  • Double positive thymocytes

    • What function do T-Cytotoxic Cells perform?

  • Kill infected intracellular organisms (correct)
  • Regulate T cell maturation
  • Phagocytose pathogens
  • Assist in antibody production

    • What is the purpose of positive selection in T cell maturation?

    <p>Select T cells based on their ability to recognize MHC antigens</p> Signup and view all the answers

    Which of the following statements about T-Suppressor Cells is correct?

    <p>They are responsible for immune response regulation</p> Signup and view all the answers

    What happens during negative selection of T cells?

    <p>T cells that react with self-antigens are eliminated</p> Signup and view all the answers

    Which statement about the MHC restriction in T cell selection is true?

    <p>Survival is contingent on the ability to react with host MHC</p> Signup and view all the answers

    Thymocytes express both CD4 and CD8 on their surface, but which statement accurately describes their classification?

    <p>They remain classified as double positive until further maturation</p> Signup and view all the answers

    What is a primary characteristic of IgM?

    <p>It excels at complement fixation.</p> Signup and view all the answers

    Which immunoglobulin type has an SC that protects it from enzymatic digestion?

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

    Which chromosomes contain the genes coding for specific immunoglobulin chains?

    <p>Chromosome 14 and 2</p> Signup and view all the answers

    What do the constant and variable portions of immunoglobulin chains get coded by?

    <p>Separate genes that can be assembled</p> Signup and view all the answers

    How long does it typically take for the primary response to an antigen to become detectable?

    <p>5 to 7 days</p> Signup and view all the answers

    Which subclass of immunoglobulin has the largest hinge region?

    <p>IgG3</p> Signup and view all the answers

    Which immunoglobulin subclass is least effective in mediating complement activation?

    <p>IgG2</p> Signup and view all the answers

    What is the role of Fc receptors on macrophages, monocytes, and neutrophils?

    <p>To enhance phagocytosis of IgG</p> Signup and view all the answers

    How many amino acids are generally contained in the light chains of immunoglobulins?

    <p>200-220</p> Signup and view all the answers

    Which immunoglobulin subclass primarily provides immunity by crossing the placenta?

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

    What distinguishes the heavy chains in immunoglobulins?

    <p>They determine the class of immunoglobulin</p> Signup and view all the answers

    Which statement about the majority of hemolytic disease of the newborn (HDN) cases is correct?

    <p>They are caused by IgG</p> Signup and view all the answers

    What is the impact of a high diffusion coefficient of IgG?

    <p>Enhances its ability to enter extravascular spaces</p> Signup and view all the answers

    Which type of light chains can be present in immunoglobulins?

    <p>Kappa and lambda</p> Signup and view all the answers

    Which of these functions is primarily associated with IgG?

    <p>Neutralizing toxins and viruses</p> Signup and view all the answers

    What is the primary purpose of monoclonal antibodies?

    <p>Used primarily for diagnostic testing and therapeutic purposes</p> Signup and view all the answers

    What is the function of the hybridoma in monoclonal antibody production?

    <p>To fuse activated B-cells with cancerous myeloma cells</p> Signup and view all the answers

    Which of the following is true about the genes involved in immunoglobulin synthesis?

    <p>Multiple genes control the synthesis of immunoglobulins</p> Signup and view all the answers

    What are the segments involved in generating the variable region of immunoglobulins?

    <p>VH, D, and J segments</p> Signup and view all the answers

    How are monoclonal antibodies developed?

    <p>By fusing a cancerous cell with an antibody-producing cell</p> Signup and view all the answers

    What is the main characteristic of the L chains in immunoglobulins?

    <p>They lack a D region</p> Signup and view all the answers

    In the context of monoclonal antibodies, what does 'pre-endowed' refer to?

    <p>Their readiness to respond to one particular antigen</p> Signup and view all the answers

    What deficiency does the myeloma cell exhibit in the hybridoma process?

    <p>A deficiency of HGPRT</p> Signup and view all the answers

    What is the primary function of Secretory IgA in the mucosal surfaces?

    <p>Acts as a first line of defense</p> Signup and view all the answers

    Which immunoglobulin is known as the 'primary response antibody'?

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

    What is the molecular shape and configuration of IgM?

    <p>Pentamer held together by J chains</p> Signup and view all the answers

    Which immunoglobulin cannot cross the placenta due to its molecular weight?

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

    Which immunoglobulin plays a major role in immediate hypersensitivity reactions?

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

    What is the distinguishing characteristic of IgD?

    <p>Found on the surface of immunocompetent B lymphocytes</p> Signup and view all the answers

    What are the two subclasses of IgA primarily distinguished by?

    <p>Presence in serum versus secretions</p> Signup and view all the answers

    What is one of the functions of IgG?

    <p>Participates in agglutination as well as opsonization</p> Signup and view all the answers

    Which statement is true regarding the half-life of IgM compared to IgG?

    <p>IgM has a shorter half-life than IgG</p> Signup and view all the answers

    What occurs during the binding of IgE to basophils and mast cells?

    <p>Degranulation and release of vasoactive amines</p> Signup and view all the answers

    What is the main role of IgA in mucosal defense?

    <p>Preventing bacterial adherence to mucosal surfaces</p> Signup and view all the answers

    What distinguishes the binding capabilities of IgG compared to IgM during precipitation reactions?

    <p>IgG binds more effectively due to smaller size</p> Signup and view all the answers

    What causes the production of specific receptors for serum and secretory IgA on leukocytes?

    <p>Cytokine signals from T cells</p> Signup and view all the answers

    Which immunoglobulin primarily plays a role in fighting parasitic infections?

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

    Study Notes

    Hematopoiesis and T Lymphocytes

    • Hematopoiesis occurs in three stages: Yolk sac (initiates lymphocyte production) → Liver → Bone marrow.
    • T lymphocytes are key players in the immune response and are involved in antibody regulation.
    • T lymphocyte maturation starts in the bone marrow, where undifferentiated thymocytes are generated.
    • Thymocytes express both CD4 and CD8 markers but are classified only after undergoing selection processes.

    T Lymphocyte Selection

    • Positive selection: Allows T cells with functional T cell receptors (TCRs) that recognize self-MHC antigens to survive.
    • Negative selection: Eliminates T cells that react with self-antigens to prevent autoimmune responses, resulting in apoptosis.
    • MHC restriction: Only T cells reacting with host MHC molecules survive.

    Subtypes of T Lymphocytes

    • T-Helper Cells: 70%, CD4(+) - predominant, assist in antibody production.
    • T-Suppressor Cells: 30%, CD8(+) - second most numerous.
    • T-Cytotoxic Cells: CD8(+) - directly kill infected intracellular organisms.

    Immunoglobulin Structure and Types

    • Immunoglobulins consist of heavy and light chains with variable and constant regions.
    • IgG is the most abundant immunoglobulin, playing a major role in neutralizing toxins and viruses, found primarily in serum.

    Major Functions of Immunoglobulin G (IgG)

    • Fixes complement: Activates the complement system.
    • Opsonization: Coats antigen to enhance phagocytosis.
    • Neutralizes toxins and viruses: Prevents their harmful effects.
    • Smallest immunoglobulin type, allowing better diffusion for immunological responses.

    Immunoglobulin M (IgM)

    • Known as macroglobulin; a pentameric structure aiding in agglutination.
    • Accounts for 5% to 10% of serum immunoglobulins, having a half-life of 6 days.
    • Primarily seen as a monomer on B cell surfaces and as a pentamer in secretions.
    • Functions in complement activation and opsonization.

    Immunoglobulin A (IgA)

    • Represents 10% to 15% of serum immunoglobulins; exists as a monomer or a dimer.
    • Secretory IgA found in mucosal areas acts as a first line of defense, neutralizing toxins and preventing bacterial adherence.
    • High valency and protective features against enzymatic digestion in mucosal defense.

    Immunoglobulin D (IgD)

    • Found on the surface of B cells and in very low serum concentrations (less than 0.001%).
    • Plays a key role in B-cell activation and regulates B-cell maturation and differentiation.

    Immunoglobulin E (IgE)

    • Represents only 0.0005% of serum immunoglobulins; involved in allergic reactions.
    • Bind to mast cells and eosinophils, triggering inflammatory responses upon antigen recognition.
    • Significant in responses to parasitic infections.

    Gene Organization and Antibody Production

    • Immunoglobulin gene clusters on chromosomes: H chain genes on 14, kappa on 2, lambda on 22.
    • Rearrangement of genes is required for the synthesis of functional antibodies.
    • The primary immune response (IgM) occurs within 5 to 7 days, with subsequent responses (IgG) being faster and more robust.

    Monoclonal Antibodies

    • Created by fusing an activated B-cell with a myeloma cell, resulting in hybridoma capable of producing specific antibodies.
    • Widely used in diagnostics and therapy due to their specificity and ability to deliver therapeutic agents.

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    Description

    Explore the three stages of hematopoiesis, highlighting the critical sequence from the yolk sac to the liver and ultimately to the bone marrow. This quiz also delves into the characteristics of thymocytes, particularly their expression of CD4 and CD8, and the implications for classifying double positive cells.

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