Systemic Lupus Erythematosus Flashcards
What is the female to male ratio?
1:9
What race’s is SLE more prevalent in?
Afro-Caribbean, Asian, Chinese
What are the genetic associations?
Multiple genes: - Fc receptors, IRF5, CTLA4, MHC class 2 HLA genes
Complement deficiency – C1q and C3
What are the clinical features of SLE?
Presentation:
- Malaise, fatigue, fever, weight loss, lymphadenopathy (lymphomas excluded)
Specific features:
- Butterfly rash, alopecia, arthralgia and Raynaud’s phenomenon
Other features:
- Inflammation of the kidney, CNS, heart & lungs
- Accelerated atherosclerosis
- Vasculitis
ACR criteria for diagnosis – 4+/11 symptoms
What are the apoptotic defects of SLE?
There is impaired clearance associated with inflammation of apoptotic bodies in SLE
The apoptotic bodies linger in the body and expose nuclear antigens on their surface which generate autoantibodies
Describe the B-cell hyperactivity of SLE
Overactive b-cells are exposed to the autoantigens and the plasma cells begin to produce auto-ABs which form immune complexes
This deposits in tissues (mainly kidneys/skin) which then activates complement in the tissues
How are autoantibodies formed in SLE?
- Abnormal clearance of apoptotic bodies
- Dendrites take up autoantigens -> b-cell activation
- B-cell Ig-class switch and affinity maturation
- IgG-autoantibodies
- Immune complexes
- Complement activation via classical pathway
How does laboratory testing help diagnose SLE?
send a serum to check for anti-nuclear antibodies - NOT diagnostic of SLE
Serum is combined with cells and if ANAs (antinuclear antibodies) are present, they will bind to the cells’ nuclear antigens. A fluorescently labelled AB is added that binds to ANAs and you observe the pattern of attachment
What other tests can be done to diagnose SLE?
- increased complement consumption
- anti-cardolipin antibodies
- lupus anticoagulant
- B1 glycoprotein
What are the heamatological and renal features of SLE?
haematological:
- lymphopaenia, normochromic anaemia
- leukopaenia, AIHA, thrombocytopaenia
renal:
- proteinuria, haematuria
- active urinary sediment
How can you assess the severity of SLE?
- Identify pattern of organ involvement
- Monitor function of affected organs:
- Renal – BP, U&E, urine sediment GFR
- Lungs/CVS – lung function tests, echocardiography - Identify the patterns of autoantibodies expressed
- Anti-dsDNA, anti-Sm – high levels of these ABs can predict renal disease
- Anti-cardiolipin antibodies
What are laboratory markers of SLE?
- ESR (rises if disease becomes more severe)
- increased complement consumption
- increased anti-dsDNA
- other Abs e.g ANA and CRP poor indicators
How can SLE be divided into groups?
- Mild – no sign of organ involvement
- Moderate/severe – organ involvement
What are the treatments for mild SLE?
- Paracetamol ± NSAIDs (monitor renal function)
- Hydroxychloroquine (arthropathy, cutaneous manifestations)
- Topical corticosteroids
What is the treatment of moderate SLE?
- Hydroxychloroquine and NSAIDs will stop working in moderate disease
- Moderate SLE indicates switch or topical -> oral glucocorticoids
> High dose and titrate down
> High dose needed to supress disease activity but also is very toxic so can give the corticosteroids with steroid-sparing agents to lower the dose required
