Immunology and Inflammatory Responses

Structure and Function of the Immune System

• The immune system's primary purpose is to recognize "self" from "non-self" and initiate responses to eliminate "non-self" foreign matter, known as antigens.
• The immune system acts to neutralize, eliminate, or destroy microorganisms that invade the body's internal environment before the invaders can multiply or overwhelm the body's defense mechanism.

Components of the Immune System

• All cells have specific cell surface markers called Major Histocompatibility Complex (MHC) that are unique to the individual.
• The body consists of several complex, overlapping protective systems, including:
  • Intact skin
  • Secretions
  • Stomach acid
  • Coughing and sneezing
• The immune system includes two major components:
  • Primary lymphoid organs (thymus, bone marrow, and probably the liver)
  • Secondary lymphoid organs (spleen, lymph nodes, and gut-associated lymphoid tissue)

Function of the Immune System

• Nonspecific immune defenses offer immediate but short-term protection, generating signs and symptoms (redness, heat, swelling, and pain), and mobilize leukocytes (phagocytosis).
• Specific (adaptive) defenses include:
  • Humoral (antibody) immunity:
    • IgA: viral protection
    • IgD: function unknown
    • IgE: allergy and parasitic infection
    • IgG/IgM: bacterial protection
  • Cell-mediated (cellular) immunity (CMI):
    • Protection against most viral, fungal, and protozoal infections and slow-growing bacterial infections such as TB
    • Probable immune surveillance for malignant cells

Hypersensitivity Reactions

• Type I reaction: an allergic or atopic reaction mediated by IgE
• Type II reaction: caused by activation of the complement system, especially protein fragments 3a and C5a
• Type III reaction: an antigen-antibody reaction that affects the vascular endothelium
• Type IV reaction: contact dermatitis

Immune System Disorders

• Chronic infections
• Fever
• Pruritus
• Difficulty breathing
• Joint pain
• Risk factors for immune system disorders:
  • Prenatal history (maternal exposure to HIV/AIDS)
  • Personal risk factors (substance abuse)
  • Family history (autoimmune disorders)

Nursing Assessment and Diagnosis

• Health history: elicit a description of symptoms, including onset, duration, location, and precipitation
• Physical examination: VS, inspection, palpation, auscultation
• Laboratory studies and diagnostic tests: CBC, Erythrocyte Sedimentation Rate
• Nursing diagnoses:
  • Risk for infection
  • Imbalanced nutrition: less than body requirements
  • Acute or chronic pain
  • Impaired physical mobility
  • Impaired social interaction