immunology

Immunology Notes

Unit 6 Overview

  • This unit covers various components of the immune system, its functioning, and factors influencing its effectiveness, as well as the systematic assessment of immune health.

Organ of the Immune System

  • Skin: First barrier of defense.
  • Mucous Membranes: Lines body cavities and secretes mucus to trap pathogens.
  • Spleen: Filters blood and helps in immune response.
  • Tonsils (Adenoids): Guard against pathogens entering through the mouth and nose.
  • Thymus: Site for T cell maturation.
  • Lymphatic System:
    • Nodes: Filter lymph and house immune cells.
    • Vessels: Transport lymph throughout the body.
  • Bone Marrow: Source of all blood cells including lymphocytes.
  • Peyer's Patches: Lymphoid tissues found in the intestines, monitoring intestinal bacteria.

Functions of the Immune System

  • Defense Mechanism: Protects against invasion by foreign pathogens and allows for rapid response.
  • Factors Affecting Function:
    • Central nervous system integrity.
    • General physical and emotional status.
    • Dietary patterns.
    • Medications.
    • Stress from illness, trauma, or surgery.
  • Surveillance: Constant mechanism to identify and reject foreign invaders.

Natural Immunity

First Line Defenses

  • Nonspecific Defenses: Broad defenses that do not target specific pathogens.
  • White Blood Cell Action (Leukocytosis):
    • Increase in leukocytes occurs in response to invasion, inflammatory response, injury, or cellular death.
  • Physical Barriers:
    • Intact skin, mucous membranes, cilia of the respiratory tract.
  • Chemical Barriers:
    • Mucus, acidic secretions in the stomach, enzymes in tears and saliva, substances in sweat and sebaceous secretions.
  • Inflammatory Response: Triggered by tissue injury, involving increased blood flow and attraction of leukocytes.
  • Regulation:
    • Must maintain balance: robust enough to eliminate antigens without causing allergies or autoimmune diseases.

Inflammatory Process

  • Initial Injury: Caused by physical, chemical agents, or pathogens:
    • Capillary Widening: Increases blood flow to the affected area.
    • Increased Permeability: Allows substances to enter tissues.
    • Attraction of Leukocytes: Draws immune cells to site of injury.
    • Fluid Release: Accumulation in tissues leads to swelling.
  • Systemic Response:
    • Fever and increased leukocyte proliferation in response to the injury.
  • Signs of Inflammation: Heat, redness, swelling, tenderness, and pain.

Acquired Immunity

  • Development: Results from exposure to antigens, either through immunization or infection.
  • Adaptation: Generates a protective immune response available on re-exposure to the same antigen.
  • Active Acquired Immunity:
    • Developed by one's own immune system (e.g., vaccination).
  • Passive Acquired Immunity:
    • Provided temporarily from an external source:
    • From mother to infant in utero or through breast-feeding.
    • Via injections of immune globulins.

Response to Invasion

  • Phagocytic Immune Response: Initial response by macrophages.
  • Humoral Response: Involves production of antibodies.
  • Cellular Immune Response: Involves T cells like helper T cells, natural killer cells, and cytotoxic T cells.

Four Stages of an Immune Response

  1. Recognition Stage: Differentiation between self and non-self entities.
  2. Proliferation Stage: Lymphocytes return to lymph nodes, stimulated to enlarge, divide, and proliferate.
    • T lymphocytes differentiate into cytotoxic/Killer T cells; B lymphocytes produce antibodies.
  3. Response Stage: Differentiated lymphocytes function in a humoral or cellular manner—both responses often involved.
  4. Effector Stage: Eventual interaction of antibodies or Killer T cells with antigens, indicating a response to infection or transplantation.
    • Transplant Rejection: Typically cell-mediated. Bacterial infections and sepsis primarily involve humoral responses.

Humoral Response

  • Action: Production of antibodies by B lymphocytes in response to specific antigens.
  • Role of Helper T Cells (CD4 cells):
    • Monitor for non-self markers. When an antigen is detected, they facilitate antibody production:
    • Process: CD4 cells present antigens to B lymphocytes, prompting them to produce specific antibodies, which are large molecules known as immunoglobulins.
  • Function of Antibodies:
    • Attach to cells with foreign antigens and mark them for destruction by Killer T cells, as well as facilitating the release of other immune-enhancing substances like histamine.

Cellular Immune Response

  • Helper T Cells: Secrete cytokines to activate B cells, cytotoxic T cells, and macrophages.
  • Cytotoxic T Cells: Directly attack antigens.
  • Suppressor T Cells: Regulate immune response by decreasing B-cell production, ensuring response is adequate without harming healthy tissues.
  • Memory T Cells: Remember previous antigen exposures for quicker responses in future encounters.

Assessment of the Immune System

Key Factors

  • Health History: Gather comprehensive medical history, including:
    • Gender.
    • Gerontologic considerations (aging factors).
    • Nutrition.
    • Immunization status.
    • Infection history.
    • Allergies.
    • Chronic disorders and diseases.
    • Medications and blood transfusions.

Physical Assessment

  • Refer to additional charts/documents for detailed methodologies.

Gender Considerations

  • Autoimmune diseases are more prevalent in females due, in part, to sex hormones that influence lymphocyte maturation and antibody production.

Gerontologic Considerations

  • Effects of aging include:
    • Bone marrow defects and suppression.
    • Decrease in macrophages, T cells, and overall cytotoxicity, leading to increased infections and metabolic disease risks.
    • Loss of self/non-self discrimination, resulting in higher cancer incidence due to failure in surveillance system.

Nutrition's Role in Immune Function

  • Protein Reserve Depletion: Leads to atrophy of lymphoid tissues and decreases antibody response, increasing infection susceptibility.
  • Nutritional Needs During Infection: May alter healing responses requiring additional nutrients.
  • Key Nutrients:
    • Zinc: Vital for immune function and apoptosis.
    • Iron: Necessary for optimal function of the immune system.
    • Protein Levels: Total protein, albumin, and pre-albumin levels are crucial measures.

Immunizations

  • Importance of vaccines in childhood and adult healthcare:
    • Prominent vaccines include flu, HPV, measles, pertussis.
  • Immunization records should reflect vaccinations and any boosters received.

Infections

  • Exposure history to:
    • Sexually transmitted infections (STIs).
    • Blood-borne pathogens (HIV, Hepatitis).
  • Document past and present infections with detailed treatments and notes on recurrent issues or unknown causes.

Allergies

  • Document history pertaining to:
    • Medications.
    • Food allergies.
    • Environmental allergens (dust, pet dander, chemicals).
    • Ensure continuous assessment for allergic reactions.

Disorders & Diseases

Autoimmune Disorders

  • Examples include Lupus, Rheumatoid Arthritis (RA), multiple sclerosis, psoriasis:
    • Document the onset, severity, remissions, treatments, and how they affect functionality.

Neoplastic Diseases

  • History of cancer, family history of cancer needs to be assessed.

Chronic Illness & Surgery

  • Conditions such as Chronic Obstructive Pulmonary Disease (COPD), Diabetes Mellitus (DM), Congestive Heart Failure (CHF), Chronic Kidney Disease (CKD), and issues with uremic toxins.
  • Document any history of organ transplants or removal of lymphoid tissues (e.g., lymph nodes, spleen).

Medications & Blood Transfusions

  • Relevant medications affecting immune function include:
    • Antibiotics, corticosteroids, cytotoxic agents, salicylates, NSAIDs, anesthetic agents, and antipsychotics (e.g., Clozaril).
  • Record any history of blood transfusions.

Lifestyle Factors

  • Factors impacting immune health include:
    • Poor nutrition.
    • Smoking.
    • Alcohol use (ETOH).
    • Illicit drug use.
    • Exposure to infections (STIs).
    • Occupational and residential exposure to hazardous substances (radiation/pollutants).
    • Psychological and physical stressors.