EMRGI - IMMUNOLOGY

• Immunology is the study of the immune system, which is a complex network of organs, cells, and proteins that defends the body against infection while protecting the body's own cells
• Hematopoiesis is the creation of a stem cell
• There are 2 types of Stem Cells: Lymphoid (B lymphocytes and T lymphocytes) and Myeloid (erythrocytes, leukocytes and thrombocytes)
• Myeloid cells include erythrocytes (RBC), leukocytes (WBC; basophils for allergic reactions: eosinophils for parasitic infection: neutrophils for bacterial infection), and thrombocytes (platelets)
• Major Histocompatibility Complex (MHC) are transplantation antigens that cause immunologic reactions against antiserum or skin grafts due to differences between donors and recipients
• MHC Class I is intracellular, synthesized in the cytoplasm, and recognized by cytotoxic CD8+ T cells; MHC Class II is extracellular, with peptide fragments recognized by CD4+ T cells
• Human Defense Mechanism: First Line of Defense: Innate Immunity includes external defenses (physical, mechanical, chemical) and internal defenses (cellular and soluble)
• Immunoglobulins directly attack antigens through agglutination, precipitating toxins, neutralizing substances, lysing cell walls, activating the complement system, anaphylaxis, and antibody-mediated hypersensitivity
• Types of Hypersensitivity:

  • Type I Anaphylactic Hypersensitivity: Allergy and Atopy involve abnormal hypersensitivity, IgE antibody production, mast cell breakdown, histamine release, and allergic reactions
  • Type II Hypersensitivity (Cytolytic/Cytotoxic): Caused by autoantibodies against self cells or tissues with foreign proteins attached
  • Type III Hypersensitivity (Immune Complex): Results from antigen-antibody complexes in tissues like skin, kidneys, pleura, and pericardium
• • Type IV Hypersensitivity (Cell-mediated/Delayed): Reaction occurs 24 to 72 hours after exposure to an allergen, examples include graft-versus-host disease, transplant rejection, contact dermatitis, and poison ivy
• Isoimmune Disease:

  • Transplant rejection occurs due to the body recognizing donor tissue as nonself and attempting to destroy it shortly after transplantation
  • HLA matching of donor and recipient enhances graft acceptance, with certain antigens like ABO, Rh, and histocompatibility antigens being crucial
• • Second Line of Defense: Inflammation Response important for tissue repair and healing, involving vascular response, plasma protein system (complement system, kinin system, clotting system)
• The immune system has two types of adaptive immunity: humoral immunity mediated by B cells and cell-mediated immunity mediated by T cells.
• Lymphocytes are white blood cells involved in the immune response, including B cells responsible for producing antibodies and T cells involved in cellular immunity.
• Lymphocytes are white blood cells involved in the immune response, including B cells responsible for producing antibodies and T cells involved in cellular immunity.
• IgG – only crosses the placenta

  IgA – fluid antigens

  IgM – food antigens

  IgE – binds to mast cells and basophils topromote allergic reaction

  IgD – antigen binding receptor on the Bcells
• Under T Lymphocytes are NK cells, Helper T cell (CD4), and macrophages which kills and cleans up dead cells
• Vascular Response happens when there is an injury/infection which causes an inflammation. There will be vasodilation thus decreasing blood viscosity and increasing permeability allowing leakage of fluids and cells. The white blood cell stick to the vessel wall, moving across the wall into the tissues called "Diapedesis" and drains into the lymphatic system
• The Plasma Protein System is inactive in the blood
• In Complement System, proteins start to interact in a cascade-like manner and aggregate the disruption of microbial cells resulting to death by lysis
• In Complement System, there is serum glycoproteins that aids in phagocytosis
• Kinin System induces vasodilation, edema, smooth muscle coordination throught stimulatio of the C-fibers
• Active Acquired Immunity

  Natural: Antigens produced throught natural exposure (ex. chickenpox)

  Artificial: Antigens produced in a vaccine (ex. COVID vaccine)
• Passive Acquired Immunity

  Natural: Antigens transferred from mother to child (ex. breastfeed)

  Artificial: Acquired from a donor (ex. blood transfusions)
• Innate Immunity

  Primary Cells: neutrophils, basophils, eosinophils, mast cells, macrophages

  Origin: RBM

  Site of Maturation: RBM

  Location of Mature Cell: lymphatics, plasma & connective tissue

  Primary Action: phagocytosis & inflammatory response
• Humoral Adaptive Immunity

  Primary Cells: antibodies

  Origin: RBM

  Site of Maturation: RBM

  Location of Mature Cell: lymphatic & plasma

  Primary Action: protection against extracellular
• Cell Mediated

  Primary Cells: cytokines

  Origin: RBM

  Site of Maturation: Thymus

  Location of Mature Cell: lymphatics & plasma

  Primary Action: protection against intracellular
• Allergy is an abnormal hypersensitivity while Atopy is a genetic predisposition to prouce large quantities of IgE, causing this state of clinical hypersensitivity
• Innate Immunity (Internal Defenses)

  • Cellular
  • neutrophils, NK cells, macrophages
  • Soluble
  • cytokines, chemokine, acute-phase proteins
  • immature mediators
  • actions: increase vascular perfusion, changes in blood flow, chematoctic migration of leukocytes at the site of inflammation
• Type I Interleukins


  type of cytokines that could inhibit tumor of growth
• Hageman Factor


  clotting factor XII

  activates the sequence of the systems (plasma protein system)