NCLEX Review Guide: Adult Health - Immune System & Immunity

Types of Immunity

• Innate immunity is the body's first line of defense, including physical barriers (skin, mucous membranes) and non-specific cellular responses that activate immediately upon pathogen exposure.
• Adaptive immunity develops specific responses to particular antigens through B-cells (humoral immunity) and T-cells (cell-mediated immunity), creating immunological memory for faster future responses.
• Active immunity occurs when the body produces its own antibodies through infection or vaccination, providing long-lasting protection.
• Passive immunity involves receiving pre-formed antibodies from another source (maternal antibodies, immunoglobulins), offering immediate but temporary protection.

Immunodeficiency Disorders

• Primary immunodeficiency results from genetic defects in immune system development, such as severe combined immunodeficiency (SCID) or DiGeorge syndrome.
• Secondary immunodeficiency develops due to external factors like HIV infection, chemotherapy, corticosteroid therapy, or malnutrition, compromising previously normal immune function.
• Opportunistic infections are the hallmark of immunodeficiency, requiring immediate assessment and intervention to prevent life-threatening complications.

Autoimmune Disorders

• Systemic lupus erythematosus (SLE) causes multi-system inflammation with characteristic butterfly rash, joint pain, and potential kidney involvement requiring immunosuppressive therapy.
• Rheumatoid arthritis primarily affects synovial joints symmetrically, causing morning stiffness, joint deformity, and systemic complications like cardiovascular disease.
• Multiple sclerosis involves autoimmune destruction of myelin sheaths in the CNS, leading to progressive neurological deficits and disability.

Types of Hypersensitivity

• Type I (IgE-mediated) reactions occur within minutes of exposure, ranging from localized urticaria to life-threatening anaphylaxis requiring immediate epinephrine administration.
• Type II (cytotoxic) reactions involve antibody-mediated cell destruction, such as hemolytic transfusion reactions or drug-induced thrombocytopenia.
• Type III (immune complex) reactions cause tissue damage through antigen-antibody complex deposition, as seen in serum sickness or certain forms of glomerulonephritis.
• Type IV (delayed-type) reactions are T-cell mediated and develop 24-72 hours after exposure, including contact dermatitis and transplant rejection.

Anaphylaxis Management

1. Assess airway, breathing, circulation immediately
2. Administer epinephrine 0.3-0.5mg IM (anterolateral thigh)
3. Position patient supine with legs elevated
4. Establish IV access and administer normal saline
5. Give supplemental oxygen and prepare for intubation
6. Administer H1 and H2 antihistamines, corticosteroids