Immunology Flashcards
What is a thyoma and what autoimmune condition is it associated with?
Thyomas = tumours originating from the epithelial cells of the thymus
Associated with neuromuscular disorders such as myasthenia gravis
What is myasthenia gravis?
An autoimmune condition that causes muscle weakness that gets progressively worse with activity and improves with rest
What type of hypersensitivity reaction is myasthenia gravis mediated by?
Type II (IgG/IgM antibody mediated)
In myasthenia gravis, what is the most common target for auto-antibodies and what does this result in?
The nicotinic acetylcholine receptors
They block the receptor so ACh can no longer bind
In the other 15% of myasthenia gravis cases, which 2 proteins are auto-antibodies created against and what do they do?
MuSK and LRP4 which are important proteins for the creation and organisation of the acetylcholine receptor
(so the receptors are destroyed in this disease)
Apart from preventing ACh binding to the nicotinic ACh receptors, what else do the auto-antibodies do?
Trigger complement system activation which results in tissue damage and destruction and the NMJ
What is rheumatoid arthritis?
An autoimmune condition which causes chronic inflammation of the synovial lining of the joints, tendon sheaths and bursa
Rheumatoid arthritis is usually caused by one high penetrance inherited mutation. T/F
False
RA is associated with many common gene polymorphisms that cumulatively increase risk of disease
Which gene family is consistently mutated in rheumatoid arthritis?
HLA DRB1 alleles within MHC
What type of hypersensitivity reaction is rheumatoid arthritis mediated by?
Type IV delayed hypersensitivity (CD4+ T cell mediated)
What is the second type of hypersensitivity reaction that may be involved in RA as the disease progresses?
Type III immune complex mediated hypersensitivity
Which antibodies in RA drive the type III hypersensitivity reactions? (2)
Rheumatoid factor (RF)
Anti-CCP antibodies
What do the CD4+ T cells that mediate RA do?
Activate tissue resident macrophages to present self-antigens to activate more effector T cells which will release pro-inflammatory mediators
List the possible effects of the pro-inflammatory mediators (e.g., TNF) released by effector T cells in RA (5)
- Recruit neutrophils to the area
- Cause synovial fibroblasts to hyperproliferate
- Cause chondrocyte dysfunction
- Promote proteolytic enzyme release from synovial fibroblasts
- Promote activation of further T and B cells
