Immunology Flashcards
define monogenic disorder
single gene defects causing AI diseases
example of a monogenic disorder
mutation in the FOXP3 gene which is needed for CD4 T cells
IPEX syndrome presents with severe infections, eczema, etc.
examples of environmental factors that can induce AI
- molecular mimicry
- intercurrent infections
- tissue damage
- superantigens
describe molecular mimicry
foreign components break tolerance to self antigens
intercurrent infections
immune responses can potentiate ongoing AI reactions
describe tissue damage
there is antigen sequestration- self antigens that were hidden from the immune system are not deleted during development and tissue damage releases these hidden antigens causing an immune reaction
describe superantigens
activate T cells non-specifically
define myasthenia gravis
autoimmune disorder characterised by severe muscle weakness and progressive fatigue
cause of myasthenia gravis
autoantibodies (IgG) that bind to ACh receptors
what is myasthenia gravis associated with?
other AI conditions such as SLE, RA and thyrotoxicosis
pathophysiology of myasthenia gravis
- CD4 T cells are activated by AChR subunits expressed by thymic epithelial cells
- effector Th cells stimulate auto-reactive B cells resulting in production of anti-AChR IgG
- thymic myoid cells are attacked and immune complexes are formed
- antibodies block binding of ACh leading to defective nerve transmission in NMJ
- AChR and endplate is eventually destroyed by complement (type II)
diagnosis of myasthenia gravis
presence of anti-AChR IgG in serum and nerve stimulation
management of myasthenia gravis
anti-cholinesterases e.g. pyridostigmine
surgery e.g. thymectomy
immunosuppressants/corticosteroids
if crisis then intubation, plasmapheresis, IVIg, etc.
