Introduction to the Immune Response and Inflammation

Introduction to the Immune Response and Inflammation

Body’s Defenses

  • Barrier defenses
  • Cellular defenses
  • Inflammatory response
  • Immune response

Barrier Defenses

  • Skin
    • Protects the internal tissues and organs of the body
  • Mucous membrane
    • Lines the areas of the body that are exposed to external influences but do not have skin protection
  • Gastric acid
    • Secreted by the stomach in response to many stimuli
  • Major histocompatibility complex
    • Distinguishes between self-cells and foreign cells

Types of Cellular Defenses

  • Mononuclear phagocyte system (MPS)
    • Composed of:
      • Thymus gland
      • Lymphatic tissue
      • Leukocytes
      • Lymphocytes
      • Numerous chemical mediators

Types of White Blood Cells—Leukocytes—Produced by the Body

Types of White Blood Cells Leukocytes Produced by the Body

Types of White Blood Cells Leukocytes Produced by the Body

 

 

Types of Leukocytes

Types of Leukocytes

Types of Leukocytes

 

 

The Inflammatory Response Hageman Factor (Factor XII)

  • A chemical in the plasma activated by cell injury
  • Responsible for activating three systems in the body
    • The kinin system
    • The clotting cascade: starts blood clotting
    • The plasminogen system: starts the dissolution of blood clots

The Role of Bradykinin

  • Causes local vasodilation
  • Stimulates nerve endings to cause pain
  • Causes the release of arachidonic acid
  • This release of arachidonic acid causes the release of autocoids

Types of Autocoids Released

  • Prostaglandins
    • Some augment the inflammatory reaction and some block it
  • Leukotrienes
    • Some can cause vasodilation and increased capillary permeability and some can block the reactions
  • Thromboxanes
    • Cause local vasoconstriction and facilitate platelet aggregation and blood coagulation

Clinical Presentation

  • Calor (heat)
    • Caused by increased blood flow
  • Tumor (swelling)
    • Caused by fluid that leaks into the tissues
  • Rubor (redness)
    • Caused by the increase in blood flow due to vasodilation
  • Dolor (pain)
    • Caused by the activation of pain fibers

Inflammatory Response

Inflammatory Response

Inflammatory Response

 

 

Immune Response

  • Specific invasions stimulate specific responses through the immune system
    • Lymphocytes produced in the bone marrow can develop into T lymphocytes or B lymphocytes
    • Other identified lymphocytes include natural killer cells and lymphokine-activated killer cells
      • These cells are aggressive against neoplastic or cancer cells and promote rapid cellular death

Types of T Cells

  • Effector or cytotoxic T cells
  • Helper T cells
  • Suppressor T cells

Function of T Cells

  • Effector or cytotoxic T cells
    • Found throughout the body
    • Aggressive against non-self cells
    • Can directly destroy foreign cells or mark cell so other cells can destroy them
  • Helper T cells
    • Stimulate the activity of B cells and effector T cells
  • Suppressor T cells
    • Monitor the chemical activity in the body
    • Act to suppress B-cell and T-cell activity when the foreign antigen is under control

Cell-Mediated Response

Cell-Mediated Response

Cell-Mediated Response

 

 

The Role of the B Cell

  • Programmed to identify specific proteins or antigens
  • Involved in humoral immunity
  • Produces antibodies or immunoglobulins

Humoral Immune Response

Humoral Immune Response

Humoral Immune Response

 

 

Response to the Varicella Virus

Response to the Varicella Virus

Response to the Varicella Virus

 

 

Other Mediators in the Immune Response

  • •nterferons
    • Prevent viral replication and suppress malignant cell replication and tumor growth
  • Interleukins
    • Chemicals secreted by active leukocytes to influence other leukocytes
  • Tumor necrosis factor (TNF)
    • Chemical released by macrophages; inhibits tumor growth and can cause tumor regression

Conditions That Cause Problems Involving the Immune System

  • Neoplasm
  • Viral invasion
  • Autoimmune disease
  • Transplant rejection

Theories of Autoimmune Disease

  • Result of response to a cell that was invaded by a virus, leading to antibody production to similar cells
  • In a state of immunosuppression, the suppressor T cells do not suppress autoantibody production
  • There is a genetic predisposition to develop autoantibodies
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