Patho 2 Exam 3

• Primary cells of adaptive immune response

  • Lymphocytes
• Humoral immunity


  B lymphocytes, produce antibodies, interact with antigens
• Cell-mediated immunity


  T lymphocytes, protects against virus-infected cells, protects against cancer cells
• Antigens

  Substances that are foreign to the body and trigger the production of antibodies
• T cells


  Found in the thymus
• B cells


  Made in the bone marrow
• Memory B and T cells

  Remember the exact antigen after the first encounter
• B lymphocyte functions

  • Produce antibodies
  • Elimination of extracellular microbes and toxins
  • Retain a memory for rapid responses
• Categories of antibodies

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


  The only immunoglobulin that crosses the placenta
• IgA


  Found in body secretions and protects against bacteria
• IgE

  Works as an inflammatory mediator and is involved in parasitic infections and allergic reactions. Bind to mast cells and basophils
• Primary immune response


  Occurs during the first encounter with antigens
• Secondary immune response


  Occurs on subsequent exposure to the antigen
• Initial vaccination


  Primary immune response
• "Booster" immunizations


  Secondary immune response
• T lymphocyte functions

  • Control of intracellular viral infections
  • Rejection of foreign tissue grafts
  • Activation of autoimmune process
• Central lymphoid organs

  • Bone marrow
  • Thymus
• Peripheral lymphoid system


  • Lymph nodes
  • Spleen
  • Tonsils
  • Appendix
  • Peyer patches in intestine
• Examples of active immunity


  • Vaccination
  • Environmental exposure
• Examples of passive immunity


  • Placenta
  • Breast milk
  • Administration of Igs
• Passive immunity


  Short-term degree of protection from infection
• Active immunity


  Usually long lasting
• Tolerance


  Ability of the immune system to react to foreign antigens but remain nonreactive to self-antigens
• Fetal development of immune responses

  Begin at 5-6 weeks
• Type I hypersensitivity disorders

  IgE-mediated reactions
• Type 1 hypersensitivity disorder


  Classic "allergic" response
• Type 1 hypersensitivity disorders

  1. Initial exposure: Exposure to antigen, allergen-specific IgE produced

  2. Secondary exposure: Allergen combines with IgE receptors on mast cells, stimulate degranulation of mast cell, histamine released
• The secondary exposure for type 1 hypersensitivity is an inappropriate immune response
• Examples of type 1 hypersensitivity reactions

  • Anaphylaxis
  • Atopic
  • Allergic rhinitis
  • Food allergies
• Type II hypersensitivity disorders


  Antibody-mediated or cytotoxic reactions
• Antibodies involved in type II and type III hypersensitivity disorders

  IgG, IgM
• Mechanisms involved with type II hypersensitivity

  • Complement-activated cell destruction
  • Complement and antibody mediated inflammation
  • Antibody-mediated cell cytotoxicity
  • Antibody-dependent modulation of normal cell surface receptors
• Examples of type II hypersensitivity disorders


  • Blood transfusion reaction
  • Rh incapability
  • Graves disease antibodies
• Type III hypersensitivity disorders


  Immune complex mediated
• Type III hypersensitivity reactions can cause clumps that can deposit in tissues in large amounts causing an inflammatory cascade
• Examples of type III hypersensitivity disorders


  • SLE
  • Acute glomerulonephritis
  • Serum sickness from antibiotics
  • Arthus reactions
• Type IV hypersensitivity disorders 


  cell mediated immune response (no antibodies involved)
• Type IV hypersensitivity


  Delayed response (24-72 hours) after antigen is presented
• Type IV hypersensitivity


  Leads to cell death and tissue injury