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
- Composed of:
Types of White Blood Cells—Leukocytes—Produced by the Body

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

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

The Role of the B Cell
- Programmed to identify specific proteins or antigens
- Involved in humoral immunity
- Produces antibodies or immunoglobulins
Humoral Immune Response

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