OCR AS Biology

Revision Notes

4.1.13 Autoimmune Diseases

Autoimmune Diseases

  • Roughly 5% of the British population suffer from an autoimmune disease
  • An autoimmune disease occurs when the body attacks itself
  • The immune system damages cells of the body as a result
  • Antibodies, T cells (helper and cytotoxic) and B cells attack one or more self-antigens
    • Glycoproteins and glycolipids form surface antigens that enable the immune system to determine whether the cell belongs to the body or if it is foreign
  • The attack can be targeted towards a single organ or it can be directed towards the entire body
  • Systemic lupus erythematosus (SLE) is an example of an autoimmune disease that affects several organs


  • Lupus is a notoriously hard disease to diagnose as the symptoms that individual present with often vary drastically
  • The most distinctive symptom of lupus is a butterfly rash across the face
  • Women tend to suffer from the disease more than men
  • The connective tissue of the body is attacked by the immune system, affecting several organs
    • Areas affected include the joints, kidneys, heart, lungs and skin
  • It causes long-term destruction

Rheumatoid arthritis

  • Rheumatoid arthritis is an autoimmune disease that solely affects the joints
    • It is different from osteoarthritis in several ways
  • It usually begins in the fingers and hands, spreading to the shoulders and elsewhere
  • Symptoms include muscle spasms, inflamed tendons, lethargy and constant joint pain

Causes of autoimmune diseases

  • The causes of autoimmune diseases are still not fully understood
  • There is a lot of research currently underway in this field
  • Scientists have deduced that genetics is an influencing factor
    • Susceptibility to an autoimmune disease was shown to be inherited
    • Susceptibility is the likelihood of an individual developing the disease when exposed to the specific pathogen or stimulus
  • However, research has also suggested that the environment is also important
    • When individuals moved from areas of low autoimmune disease prevalence (like Japan) to areas of higher autoimmune disease prevalence (like the USA) showed an increased chance of developing an autoimmune disease

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