Immune Disorders Summary

Immune Disorders

• Too little or too much immune response:

  • Hyper-immune responses:

  • Allergy

  • Autoimmunity

  • Cytokine storms

  • Hypo-immune responses:

  • Immune deficiencies

  • Immunosuppression

  • Immunity and Cancer

Allergy

• Immune hypersensitivity: adverse effects of immune reaction exceed the effects of the antigen.

• Examples:

  • Nasal/sinus inflammation from pollen.

  • Swelling from peanuts/bee stings.

  • Fatal brain swelling in cerebral malaria.

• Not all hypersensitivity reactions are allergies (e.g., upset stomach from aspirin).

Auto-Immunity

• Autoimmune diseases: immune system attacks host tissue as foreign antigen.

• Common cause: similarities between host proteins and foreign antigens.

• Example: M-protein from Group A Strep similar to human heart proteins.

Examples of Auto-Immune Diseases

• Known autoimmune diseases:

  • Rheumatic carditis, rheumatic fever, St. Vitus’ dance (related to Group A strep).

  • Rheumatoid arthritis, ankylosing spondylitis, systemic lupus, ulcerative colitis, Crohn’s ileitis, psoriasis (unknown antigens).

• Possible autoimmune diseases:

  • Insulin-dependent (type 1) diabetes linked to viral pancreatitis.

  • Multiple sclerosis (unknown foreign antigen?).

Cytokine Storms

• Term popularized during COVID-19; phenomenon recognized for centuries.

• Severe innate immune responses can lead to death due to inflammation.

• Examples:

  • Cerebral malaria: death from brain swelling, not the disease.

  • COVID-19: death from vasculitis and thrombosis.

Immune Deficiencies and Suppression

• Causes of under-performing immune systems:

  • Genetic immunodeficiencies.

  • Acquired immune deficiency (AIDS).

  • Immunosuppression from drugs for inflammatory diseases or organ transplantation (e.g., David Vetter, "Boy in the Bubble").