Notes on Immunity and Immune Disorders

Care of the Patient With an Immune Disorder

Objectives

  • Explain Immunocompetence, Immunodeficiency, and Autoimmunity:

    • Immunocompetence: Ability of the immune system to mobilize and use antibodies effectively against antigens.

    • Immunodeficiency: Failure of the immune system to respond adequately, leading to increased susceptibility to infections.

    • Autoimmunity: Occurs when the immune system erroneously attacks the body's own cells, perceiving them as foreign.

  • Differentiate Between Natural and Acquired Immunity:

    • Natural Immunity: Innate, nonspecific defenses present at birth, such as skin and mucous membranes.

    • Acquired Immunity: Develops after exposure to specific pathogens or through vaccination, which provides targeted immune responses.

  • Compare and Contrast Humoral and Cell-Mediated Immunity:

    • Humoral Immunity: Mediated by B cells, involves the production of antibodies that neutralize pathogens.

    • Cell-Mediated Immunity: Involves T cells that directly attack infected or abnormal cells.

  • Review Mechanisms of Immune Response:

    • The immune system utilizes various cells and organs to recognize, attack, and remember pathogens.

  • Discuss Factors Influencing Hypersensitivity Development:

    • Factors such as genetic predisposition, environmental triggers, and exposure to allergens can influence hypersensitivity reactions.

  • Identify Clinical Manifestations of Anaphylaxis:

    • Symptoms include difficulty breathing, swelling, hives, and a rapid drop in blood pressure, potentially leading to shock.

  • Outline Immediate Treatment for Anaphylactic Reactions:

    • Administer epinephrine, keep the patient calm, and ensure rapid availability of emergency medical services.

  • Discuss Latex Allergies:

    • Types: Type I (immediate hypersensitivity) and Type IV (delayed hypersensitivity).

    • Prevention: Use of non-latex gloves, employee training, and education on allergen avoidance in the workplace.

  • Blood Disposal Practices:

    • Selection of donors, typing, cross-matching blood types, proper storage, and administration techniques are crucial to prevent transfusion reactions.

  • Explain an Immunodeficiency Disease:

    • Examples include Acquired Immune Deficiency Syndrome (AIDS), where the immune system is severely compromised.

  • Discuss Autoimmune Disorder Causes:

    • Autoimmune disorders arise from a malfunction of the immune system that leads to attack on the body’s own tissues.

  • Explain Plasmapheresis:

    • A medical treatment to filter the blood and remove harmful antibodies in autoimmune disorders.

Key Terms

  • Adaptive Immunity:

    • Definition: The type of immunity that develops over time and can target specific pathogens.

  • Allergen:

    • Definition: A substance that can provoke an allergic reaction but is not inherently harmful.

  • Anaphylactic Shock:

    • Definition: A severe, potentially life-threatening allergic reaction that can occur quickly.

  • Antigen:

    • Definition: Any substance that can provoke an immune response, typically a protein that is foreign to the body.

  • Attenuated:

    • Definition: A weakened form of a pathogen used in vaccines to promote immunity.

  • Autoimmune:

    • Definition: Pertaining to disorders where the immune system attacks the body's own tissues.

  • Autologous:

    • Definition: Referring to tissue sourced from the same individual.

  • Cellular Immunity:

    • Definition: Immune responses that involve T cells directly attacking pathogens or abnormal cells.

  • Humoral Immunity:

    • Definition: Immune responses mediated by B cells and antibodies in the body's fluids.

  • Hypersensitivity:

    • Definition: An exaggerated immune response causing damage to the body.

  • Immunity:

    • Definition: The state of being insusceptible to a disease.

  • Immunocompetence:

    • Definition: The capacity of the immune system to mount an effective response.

  • Immunodeficiency:

    • Definition: A state of immune system inadequacy resulting in increased susceptibility to infections.

  • Immunogen:

    • Definition: An agent that provokes an immune response.

  • Immunology:

    • Definition: The branch of medicine that studies the immune system.

  • Immunosuppressive:

    • Definition: Substances that reduce the immune system's ability to prevent infections and diseases.

  • Immunotherapy:

    • Definition: Treatment designed to enhance or suppress the immune system.

  • Innate Immunity:

    • Definition: The first line of defense of the immune system, providing immediate yet nonspecific protection.

  • Lymphokines:

    • Definition: Cytokines produced by lymphocytes that influence the activity of other immune cells.

  • Plasmapheresis:

    • Definition: A procedure to remove plasma from the blood and separate its components, often used in autoimmune therapies.

  • Proliferate:

    • Definition: To increase in number, especially cells in response to an antigen.

Nature of Immunity

  • The human body faces constant challenges from harmful agents, and the immune system adapts to defend against these threats.

  • Derived from the Latin immunis meaning "free from burden," immunology focuses on the body's capacity to differentiate self versus nonself through a network of specialized cells and tissues known as the immune system or host defense system.

  • The immune system includes organs, tissues, and cells, with the primary role of protecting the body from diseases. Key functions include:

    • Pathogen Detection: Specialized cells identify and eliminate pathogens.

    • Homeostasis Maintenance: Proper immune function helps maintain stability within the body's internal environment.

    • Additional Responses: Triggers include increases in body temperature and mucus production.

Immunocompetence and Immunoincompetence

  • Immunocompetence: Adequate immune response to foreign stimuli, maintaining body integrity.

  • Immunoincompetence: Inadequate or excessive immune responses disrupt homeostasis, leading to various immune disorders:

    1. Allergies: Hyperactive responses to environmental antigens.

    2. Immunodeficiency: Disorders like AIDS or treatment-induced impairments.

    3. Autoimmune Disorders: Conditions like lupus, diabetes, rheumatoid arthritis, where the immune system attacks the self.

    4. Beneficial Tissue Attacks: Rejection of transplants or transfusion reactions.

Definitions of Immunity

  • Immunity: The state of being resistant to specific diseases, divided into:

    • Innate (Natural) Immunity: Nonspecific defenses present at birth.

    • Adaptive (Acquired) Immunity: Specific responses developed after exposure to antigens (see Fig. 55.1).

Innate (Natural) Immunity

  • The body's initial defense line includes physical and chemical barriers:

    • Physical Barriers: Skin, mucous membranes, cilia, and secretions like saliva and hydrochloric acid.

    • Immune Response Mechanisms: Phagocytes (neutrophils, macrophages) and inflammatory responses serve as nonspecific defense.

Components of Innate Immunity

  • Phagocytes: Cells that detect, engulf, and destroy pathogens. They migrate to infected areas and help activate additional immune responses.

Adaptive (Acquired) Immunity

  • If innate responses fail, the adaptive immune response is activated:

    • Specific Response: Tailored action against particular antigens with immunologic memory.

    • Cell Types: Comprised of T cells and B cells. T cells (70%-80% of lymphocytes) manage cellular immunity while B cells (20%-30%) handle humoral responses.

T Cells and B Cells

  • T Cells:

    • Release lymphokines to attract and activate macrophages.

    • Essential for cell-mediated immunity, impacting responses against infections and malignancies.

  • B Cells:

    • Produce antibodies to combat foreign antigens and are vital for humoral immunity.

Humoral Immunity

  • Mediated through B cells and antibodies. The initial response to an antigen is slow (primary response), while a quick response occurs upon subsequent exposures (secondary response). Immunizations enhance this memory.

T Lymphocyte Subsets

  • T-Helper (CD4): Activate and coordinate immune responses by stimulating B cell antibody production.

  • T-Suppressor (CD8): Regulate and maintain balance in the immune response to avoid overactivity.

Immunity Classes

  • Active Immunity: Developed through infection or vaccinations, the body produces its antibodies.

  • Passive Immunity: Provided by external antibodies, such as maternal transfer

  • during pregnancy or through breast milk. Examples also include antibody injections for exposure prevention.

Mechanism Activation by Antigen Exposure

  • When antibodies and antigens interact, they can activate:

    • Complement System: Composed of approximately 25 serum enzymes active during an immune response that aids in destroying pathogens.

    • Antigen-Antibody Reaction: Triggers histamine release from mast cells, leading to allergy symptoms.

Cellular Immunity

  • Characterized by T cells responding to specific antigens. It is crucial for combating intracellular pathogens, including viruses. T cells become sensitized upon exposure, providing targeted immunity against specific antigens but can also lead to transplant rejection and autoimmune diseases.