Autoimmune disease Flashcards
Describe the mechanism of Grave’s disease
body produces anti-TSHR antibodies in thyroid –> TSH receptors act as antigens for those antibodies, so autoantibodies bind TSH receptor –> overactivity of TSH receptor –> hyperthyroidism
how is systemic lupus erythematosus caused?
antibodies to nuclear antigens e.g. double stranded DNA produced
what is central tolerance of immune system?
when immune system destroys destroys T + B cells that can attack self-proteins before they enter circulation
what is peripheral tolerance of immune system?
when immune system destroys/controls self-reactive T + B cells after they’ve entered circulation
Explain the role of T + B cells in central tolerance
If immature B cells in bone marrow encounter an antigen that can cross-link with their IgM –> apoptosis is triggered.
T cells recognise antigens presented to them by MHC proteins, they do this by identifying MHC complex and then recognise whether the peptide presented is foreign or the MHC is self
what is an autoimmune regulator (AIRE) and what does it do?
a specialised transcription factor, allowing protein expression which would normally only be expressed in a particular tissue. Promoting self-tolerance by allowing thymic expression of genes from other tissues, making sure all proteins are in the thymus so T cell can see them
what are the 3 mechanisms of peripheral tolerance
anergy
ignorance
regulation
what is meant by citrullination
citrullin is an AA not coded for by DNA. Arginine can be converted to citrulline as post-transitional modification by peptidylarginine deminase (PAD) enzymes
explain the mechanism of rheumatoid arthritis
autoantibodies to citrullinated proteins produces in rheumatoid arthritis
describe the mechanism of myasthenia gravis
autoantibodies bind Ach receptor –> block acetylcholine’s ability to bind –> receptor internalisation and degradation –> activation of complement and phagocytic cells
