autoimmunity

Question 1

autoimmunity

Answer 1

adaptive immune response specific for self antigen, leading to inappropriate tissue damage or physiological dysfunction
- autoantigens
- autoreactive cells (cells that react to the autoantigens)
- autoantibodies

Question 2

pathogenesis of autoimmune disease

Answer 2

1. inheritance of susceptibility genes
   - polygenic susceptibility (accumulation of multiple minor gene mutations + environmental factors = autoimmune disease)
   - (rare) single gene defects
   -> AIRE (loss of self tolerance -> cannot identify T cells that will react to self antigens)
   -> Foxp3 or CTLA4 (loss of ability to suppress immune response)
2. closely associated with MHC alleles
   - affect T cell function
   - MHC inefficient at presenting specific self antigen (defective negative selection)
3. women more prone to autoimmune conditions
   - incidence of autoimmune disease highest during reproductive years, declines during menopause -> decline in oestrogen
4. environmental targets -> UV,

Question 3

mechansims of autoimmunity

Answer 3

• anaphylatoxins (C3a, 5a) -> neutrophil activation
• opsonisation (C3b) -> immune complexes too big for phagocytosis, leading to frustrated phagocytosis and release of lysosomal enzymes and reactive oxygen species into ECF

result in tissue injury and inflammation

Question 4

SLE

Answer 4

systemic lupus erythematosus

symptoms: painful joints, rash, kidney issues

pathogenesis: anti dsDNA antibodies target nucleus. immune complexes formed deposit in organs and joints pathological deposition of immune complexes in tissues (multi-organ deposition) -> trigger inflammation (type 3)

risks: gender (female), genes (MHC, complement), environment (UV light, oestrogen, infection)

tests:
urine dipstick -> proteinuria
serum anti dsDNA antibodies (specificity)
serum anti nuclear antibodies (sensitive)