NURS 311: Immunity (Giddens)

Age-Related Normal Differences in Immune Function

  • Immune System Development: The immune system begins as immature in utero, accepting maternal alloantigens, and shows gradual maturation through exposure to antigens during childhood.

  • Pregnancy and Immunity: During pregnancy, the fetal immune response is minimal, and the mother's immune system tolerates the fetus, preventing rejection without immunosuppression.

  • Elderly Immunity Decline: Age brings a decline in immunity, increasing the risk for infections and diminishing vaccine efficacy, linked to a decrease in self-antigen recognition and an increase in autoimmune diseases.

Primary Immunodeficiency (PI)

  • Definition: A condition where the immune system is inadequate due to missing components, with over 200 types identified by NIH.

  • Warning Signs of PI:

    • Four or more new ear infections within 1 year.

    • Two or more serious sinus infections within 1 year.

    • Prolonged use of antibiotics with little effect.

    • Two or more pneumonias within 1 year.

    • Failure to grow or gain weight in infants.

    • Recurrent deep skin or organ abscesses.

    • Persistent thrush or skin fungal infections.

    • Need for IV antibiotics.

    • Two or more deep-seated infections, including septicemia.

    • Family history of PI.

  • Common Variable Immunodeficiency: Characterized by defects in antibody formation from B lymphocytes, critically impacting plasma cell differentiation.

Immune Response Variations

  • Diminished Immune Functioning: Can range from mild symptoms to severe consequences, including life-threatening infections and organ dysfunction from cancer.

  • Exaggerated Immune Response: Classified into four hypersensitivity types:

    • Type I: IgE-mediated (e.g., allergies)

    • Type II: Tissue-specific or cytotoxic reactions.

    • Type III: Immune complex-mediated reactions (e.g., systemic lupus erythematosus).

    • Type IV: Cell-mediated or delayed hypersensitivity (e.g., transplant rejection).

Consequences of Immunosuppression

  • Infection Risks: Immunocompromised individuals are more susceptible to infections, including emerging superinfections like MRSA and C. difficile.

  • Cancer Connection: Immunocompromised states, particularly in the elderly, show an increased prevalence of certain cancers.

Consequences of Exaggerated Immune Response

  • Autoimmune Diseases: Can lead to multisystem diseases, including rheumatoid arthritis and systemic lupus erythematosus (SLE).

  • Potential Damage: Illnesses may arise from autoimmunity, resulting from the immune system attacking the body’s own tissues.

Risk Factors for Immunity Dysfunction

  • Age-related Factors: Very young (immature immune system) and elderly (declining immune function) populations are at higher risk for infections.

  • Chronic Illnesses: Diseases such as diabetes and cancer can depress immune function.

  • Environmental Factors: Poor nutrition and exposure to pollutants contribute to immune dysfunction.

  • Genetics: Genetic predisposition can lead to immune deficits or exaggerated responses to antigens.

  • High-Risk Behaviors: Behaviors like unprotected sex and substance abuse can increase the risk of infection.

Assessment of the Immune Response

  • History taking: A comprehensive health history is crucial to assess risk factors and identify symptoms linked to immune dysfunction.

  • Physical Examination: Clinical indicators include checking lymph nodes, wounds, and any signs of infections.

  • Diagnostic Tests: Blood tests including red and white blood cell counts, screening for specific autoantibodies, and allergy testing are standard tools for immune assessment.

Clinical Management

  • Primary Prevention: Vaccination is critical across the lifespan.

  • Secondary Prevention: Screening for immune disorders is important, focusing on at-risk populations.

  • Collaborative Interventions: Treatment strategies will differ based on whether the dysfunction is immunosuppressive or exaggerated.

Examples of Immune Dysfunction

  • Suppressed Immune Response: Conditions such as HIV, Hodgkin lymphoma, and primary immunodeficiency.

  • Exaggerated Immune Response: Allergic reactions, autoimmune diseases such as type 1 diabetes and systemic lupus erythematosus.

Clinical Exemplar Cases

  • HIV Disease: Infection leading to CD4 T cell destruction and subsequent immune deficiency that increases vulnerability to opportunistic infections.

  • Anaphylaxis: Extreme allergenic reactions like those from food or drugs can range from mild to life-threatening, requiring immediate medical intervention.

  • Systemic Lupus Erythematosus (SLE): An autoimmune condition characterized by a butterfly rash and multi-organ impact.

  • Type 1 Diabetes Mellitus: Destruction of pancreatic beta cells leading to insulin deficiency and metabolic complications.

  • Multiple Sclerosis: A neurological condition caused by an autoimmune attack on myelin, affecting communication between nerves and muscles.