Lesson 4

• Immunity and Immune Response

  Lecture 4
• Immune System


  Responsible for the body's protection or defense against invading pathogens
• Composition of the immune system

  • Lymphoid organs, cells and tissues, and chemical mediators
• Lymphoid organs


  • Lymph nodes
  • Spleen
  • Tonsils
  • Intestinal lymphoid tissue
  • Lymphatic circulation
• Lymphoid cells


  • Lymphocytes
  • Macrophages
• Lymphoid tissues for immune cell production

  • Bone marrow
  • Thymus
• Chemical mediators


  • Histamines
  • Interleukins
  • etc.
• Primary lymphoid organs


  • Bone marrow
  • Thymus
• Secondary lymphoid organs


  • Spleen
  • Lymph nodes
  • Mucosa-associated lymphoid tissue (MALT)
  • Cutaneous-associated lymphoid tissue (CALT)
• Lymphocytes


  Primary leukocytes in immune responses (immunocompetent cells)
• Types of lymphocytes


  • B lymphocytes (B cells)
  • T lymphocytes (T cells)
  • Cytotoxic T cells
  • Helper T cells
  • NK cells
• Macrophage


  Critical initiator of immune response
• 1. cells


  Lymphocytes that matured in the thymus and are primarily involved in cell-mediated immunity
• 1. cells do not directly interact bind to antigen
• Phagocytic cells


  Present antigenic peptides to T-cells via T-cell receptors (TCRs)
• 1. cells


  Lymphocytes of humoral immunity
• Antibodies


  Coat and are produced against a specific antigen
• NK cells (natural killer cells)

  Can destroy pathogens without prior exposure
• Monocytes


  Mononuclear agranulocyte with a critical role in the initiation of the immune response
• Macrophages


  Monocytes found in tissues that intercept and engulf foreign material, process and display the antigens, and activate lymphocytes
• Macrophages


  Secrete chemicals such as monokines and interleukins that can activate additional lymphocytes and in secondary immune response
• Cells involved in Immunity

  • Lymphocytes
  • Macrophages
  • Monocytes
  • NK cells
• Chemical Mediators


  • Complement
  • Histamine
  • Kinins
  • Prostaglandins
  • Leukotrienes
  • Cytokines (messengers)
  • Tumor necrosis factor (TNF)
  • Chemotactic factor
• Antigen


  Antibody generators from the invading pathogen that can activate immune response
• Components of antigen


  • Capsules
  • Cell walls
  • Toxins
  • Flagella
• Antibody


  Soluble proteins that are produced by the host to fight off antigen
• Antibody


  Secreted by plasma cells or from the B-cell
• Types of antibodies (immunoglobulins)

  • IgM
  • IgG
  • IgD
  • IgA
  • IgE
• Immunogens


  (Macro)molecules capable of triggering (adaptive) immune response to produce antibodies
• All immunogens are antigens, but not all antigens are immunogens
• Autoantigens


  Antigens that belong to the host, no immune response under normal circumstances but may result in autoimmune disease
• Alloantigens


  Other members of the host's species; cause immune response
• Blood group antigens


  Found on the RBC surface, tissue, body fluids
• Heteroantigens


  From other species (plants, animals, or microorganisms)
• Heterophile Ag


  Hetero Ag in unrelated plants or animals but are either identical or closely related in structure and Ab can cross-react of another
• Immunoglobulins


  Glycoproteins (86-89% polypeptide; 2-14% carbohydrate)
• Immunoglobulins


  Main humoral element of the adaptive immune response and play an essential role in Ag recognition, opsonization, and complement activities
• Immunoglobulins


  Composed of heavy (H) chain and light (L) chain
• Domains


  Regions consist of 110 AA; basic unit of Ab structure
• Fc fragment


  Non Ag-binding and is the carboxy-terminal halves of 2 H chains; important in effector functions of antibodies