L19-20 - Autoimmunity Flashcards
What is autoimmunity?
Immune response against a self antigen
What is an autoantigen?
Any self protein that can trigger an immune response
What is autoimmune disease?
A build up of pathological changes resulting from an autoimmune response
What are the specific (2) and main non-specific (3) effector mechanisms of autoimmune damage?
Specific - antibodies, T cells
Non-specific - complement, phagocytes, NK cells
What are organ specific autoimmune diseases?
Give 2 examples
Damage is confined to the organ targeted in the immune response
Myasthenia gravis, Grave’s disease, T1 diabetes, autoimmune haemolytic anaemias
What are systemic autoimmune diseases?
Give 2 examples
Immune response against antigens associated with multiple tissue types
Rheumatoid arthritis, rheumatic fever, systemic lupus erythematosus, reiter’s syndrome
What are the 3 general causes of autoimmune disease?
Genetics, environmental factors, errors in immune regulation
What gene complex is most commonly associated with autoimmunity? What specifically is it associated with?
HLA complex (includes MHC genes)
The control of and susceptibility to autoimmune disease
What environmental triggers can result in autoimmune disease?
Pathogens, drugs/toxins, hormones
How do hormones affect autoimmune disease susceptibility?
Females more at risk due to oestrogen levels
Young - high oestrogen stimulates B related autoimmunity
Older - low oestrogen stimulates T related autoimmunity
How is autoimmunity involved in pregnancy?
- Rising hormones can cause abortion
- Endometriosis and preeclampsia thought to be autoimmune
What can complement deficiencies result in in terms of autoimmune disease?
CD59 and 55 deficiencies - autoimmune haemolytic anaemia
Classical pathway deficiencies - systemic lupus, rheumatoid arthritis
What is Myasthenia gravis?
Neuromuscular disorder with progressive weakness and loss of muscle control
What is the pathogenesis of Myasthenia gravis?
Autoantibodies against acetylcholine receptors (involved in muscle contraction)
What is the pathogenesis of Grave’s disease?
Autoantibodies mimic TSH and bind to TSH receptors
This increases thyroid hormone production, producing hyperthyroidism
What are the treatment options for Grave’s disease?
Ease symptoms (anxiety, high HR, sweating) with beta-blockers
Treat hyperthyroidism with anti-thyroid medication, radioactive iodine or surgery
What is the pathology of insulin-dependent diabetes mellitus?
T cell mediated autoimmunity destroys pancreatic beta cells
Reduces insulin output
What is the pathogenesis of rheumatoid arthritis?
- IgM, G and A against IgG Fc regions produced
- Immune complexes congregate in joint synovium, so reaction results in inflamed joints
What is the pathogenesis of rheumatic fever?
- Body produces antibodies against Streptococcus pyogenes during infection
- These cross-react with heart tissue
What is systemic lupus erythematosus (SLE)? What is its pathology?
Widespread tissue damage and inflammation
Autoantibodies created against cell nuclei, dsDNA, nucleoproteins, and cytoplasmic proteins (related to T and B cell hyperactivity)
How is systemic lupus erythematosus (SLE) treated?
Medication to ease symptoms as there is no cure:
- Anti-inflammatories for sore joints
- Steroid creams for rashes
- Corticosteroids for general inflammation
What is Reiter’s syndrome?
Reactive arthritis in response to infection
What are the signs of Reiter’s syndrome?
Joint inflammation (especially knees and ankles), inflammation of the eyes and urinary tract, hard nodules on the feet
What is the cause of Reiter’s syndrome?
Bacterial infection in the intestines, urinary tract, or genitals
E.g. STIs, Salmonella, Shigella
