| Value | Reference ranges | |
|---|---|---|
| Haemoglobin (g/L) | 108 | 115–155 |
| Creatinine (μmol/L) | 210 | 60–100 |
| C-reactive protein (mg/L) | 80 | <10 |
A. Systemic lupus erythematosus; anti-nuclear antibody (ANA)
B. Post-streptococcal glomerulonephritis; anti-streptolysin O titre (ASOT)
C. Goodpasture syndrome; anti-glomerular basement antibody
D. Wegener granulomatosis; anti-neutrophil cytoplasmic antibody (ANCA)
E. Cryoglobulinaemic vasculitis; cryoglobulin
23. A 46-year-old man presents with a painful and swollen left knee. He has no significant past medical history. Aspiration of the knee revealed calcium pyrophosphate crystals. The X-ray of his left knee is shown below. Which additional test should be performed?
A. Skeletal survey
B. Parathyroid hormone
C. Lactate dehydrogenase
D. Serum electrophoresis
E. Serum light chain
24. A 35-year-old woman is admitted to the Intensive Care Unit because of adult respiratory distress syndrome and multiple cerebral micro-infarctions. She has a history of recurrent miscarriages but no history of thromboembolism. Her investigations reveal a creatinine of 250 μmol/L and urinalysis showing blood +++. Which one of the following investigations should be undertaken in this patient?
A. Protein C level and anti-thrombin III level
B. Protein S level and anti-thrombin III level
C. Anti-cardiolipin antibodies
D. Anti-glomerular basement membrane antibody
E. Complement levels (C3 and C4)
25. A 43-year-old man has experienced bilateral hand pain and swelling intermittently for the past 6 months. He indicates that the second and third distal interphalangeal joints on his right hand and the fourth distal interphalangeal joint on his left hand give him the most symptoms. Physical examination reveals fingers that are markedly swollen and inflamed, but are remarkably non-tender on palpation. Range of motion is preserved. Skin examination reveals no rash; however, the scalp has several small areas of silver scaling and he reports a previous scaly rash affecting his elbows. Which one of the following changes is most likely to be found on X-ray with this patient’s condition?
A. Periarticular osteoporosis
B. Chondrocalcinosis in the wrist
C. Subchondral cysts
D. Periostitis at the distal phalanges
E. Subchondral bony sclerosis
26. Which one of the following is NOT included in the American College of Rheumatology (ACR) diagnostic criteria for systemic lupus erythematosus?
A. Alopecia
B. Non-erosive arthritis
C. Painless oral ulcer
D. Lymphopenia (<1.5 × 109 cells/L)
E. Warm antibody autoimmune haemolytic anaemia
27. A 17-year-old male with no prior medical history presented with arthralgia, abdominal pain and smoky-coloured urine. On examination a palpable rash was present on both legs (see below). Urine dipstick showed red blood cells but all other tests, including electrolytes, full blood count, liver function tests, complement levels, electrocardiography (ECG) and chest X-ray, were normal. What is the most likely diagnosis?
A. Erythema nodosum
B. Cryoglobulinemic vasculitis
C. Contact dermatitis
D. Erythema multiforme
E. Henoch–Schönlein purpura (HSP)
28. Amyloidosis is characterised by:
A. Intracellular deposition of proteins which are remnants of nuclear break down
B. Intracellular deposition of immunoglobulin light chains
C. Extracellular tissue deposition of fibrils composed of low molecular weight subunits derived from a variety of proteins, many of which circulate as constituents of plasma
D. Extracellular deposition of glycoproteins
E. Extracellular deposition of antigen–antibody complexes and complement components
29. Which one of the following is a manifestation of systemic lupus erythematosus?
A. Haemolytic anaemia
B. Leucocytosis
C. Lymphocytosis
D. Eosinophilia
E. Thrombocytosis
30. A 37-year-old woman with systemic lupus erythematosus (SLE) has been receiving glucocorticoid treatment for the past 4 years. Initially she received prednisolone 60 mg/day for 3 months, then gradually tapered down over 18 months. Her maintenance dose is 15 mg/day. She now complains of several weeks of right groin pain and difficulty in walking; the groin pain also has occurred at rest for the past few days. She reports no falls or significant trauma. What diagnosis is likely?
A. Osteoporotic fracture of the neck of femur
B. Rheumatoid arthritis affecting the right hip joint
C. Right trochanteric bursitis
D. Gout affecting the right hip joint
E. Avascular necrosis of the right femoral head
31. A 50-year-old man who presented with Horner syndrome was found to have partial internal carotid artery dissection. He was noted to have stretchy skin and hyper-mobile joints. He has several scars, especially over his legs, and on being asked about these said that he tended to get extensive scars with minimum trauma. There was no significant family history and he had no other medical issues. What is the likely diagnosis?
A. Marfan syndrome
B. Ehlers–Danlos syndrome
C. Tuberous sclerosis
D. Noonan syndrome
E. Klinefelter syndrome
Theme: Serological testing in rheumatological conditions (for Questions 32–35)
A. Anti-Scl-70 antibodies
B. Anti-double-stranded DNA antibodies
C. Anti-SSA or anti-Ro antibodies
D. Antibodies to citrullinated peptides
E. Anti-histone antibodies
F. Anti-nuclear cytoplasmic antibodies
G. Anti-ribosomal P protein antibodies
H. Anti-U1 RNP antibodies
For each of the scenarios below, select the most appropriate antibody.
32. In patients with hydralazine-induced lupus, which antibody can be detected in more than 95% of cases?
33. In a woman with systemic lupus erythematosus, the presence of which antibody is associated with her children developing congenital heart block?
34. In a patient with systemic sclerosis, which antibody is associated with increased risk of interstitial lung disease?
35. In patients with rheumatoid arthritis, which antibody is associated with an increased risk of progressive joint damage?
Answers
Basic Science
1. Answer B
Methotrexate is widely used for the treatment of rheumatoid arthritis (RA), other autoimmune conditions and in cancer chemotherapy. The mechanisms of action of methotrexate are complex. Methotrexate binds and inhibits dihydrofolate reductase. It inhibits nucleotide and DNA synthesis and cell replication by competitively inhibiting the conversion of dihydrofolate to the active tetrahydrofolate , yielding cytotoxic, immunosuppressive and anti-inflammatory action. Folinic acid rescue is usually given after methotrexate therapy to reduce myelosuppression but does not antagonise its anti-inflammatory effects.
The precise mechanism of its anti-inflammatory actions remain incompletely understood (Chan and Cronstein, 2010). There are several other pharmacological mechanisms of methotrexate action, including inhibition of purine and pyrimidine synthesis, suppression of transmethylation reactions with accumulation of polyamines, reduction of antigen-dependent T-cell proliferation, and promotion of adenosine release with adenosine-mediated suppression of inflammation. It is possible that a combination of these mechanisms is responsible for the anti-inflammatory effects of methotrexate. To date, the adenosine-mediated anti-inflammatory effect of methotrexate is the best supported by the in vitro, in vivo and clinical data. It is highly teratogenic and should be avoided in pregnancy, during breast feeding or when trying to conceive.
Methotrexate is widely used for the treatment of rheumatoid arthritis (RA), other autoimmune conditions and in cancer chemotherapy. The mechanisms of action of methotrexate are complex. Methotrexate binds and inhibits dihydrofolate reductase. It inhibits nucleotide and DNA synthesis and cell replication by competitively inhibiting the conversion of dihydrofolate to the active tetrahydrofolate , yielding cytotoxic, immunosuppressive and anti-inflammatory action. Folinic acid rescue is usually given after methotrexate therapy to reduce myelosuppression but does not antagonise its anti-inflammatory effects.
The precise mechanism of its anti-inflammatory actions remain incompletely understood (Chan and Cronstein, 2010). There are several other pharmacological mechanisms of methotrexate action, including inhibition of purine and pyrimidine synthesis, suppression of transmethylation reactions with accumulation of polyamines, reduction of antigen-dependent T-cell proliferation, and promotion of adenosine release with adenosine-mediated suppression of inflammation. It is possible that a combination of these mechanisms is responsible for the anti-inflammatory effects of methotrexate. To date, the adenosine-mediated anti-inflammatory effect of methotrexate is the best supported by the in vitro, in vivo and clinical data. It is highly teratogenic and should be avoided in pregnancy, during breast feeding or when trying to conceive.
Chan, E.S. and Cronstein, B.N. (2010). Methotrexate – how does it really work? Nat Rev Rheumatol 6, 175–178.
2. Answer D
P-ANCA-positive sera on indirect immunofluorescence, which is classically directed against the myeloperoxidase (MPO) antigen, may be associated with concomitant positivity directed against a variety of other neutrophil antigens, such as bactericidal permeability inhibitor (BPI), cathepsin G and lactoferrin (Wong et al., 2000).
In vasculitis, the two target antigens for ANCA are proteinase 3 (PR3) and myeloperoxidase (MPO). Both PR3 and MPO are located in azurophilic granules in the cytoplasm of neutrophils and peroxidase-positive lysosomes of monocytes.
Two types of ANCA assay are indirect immunofluorescence using alcohol-fixed buffy coat leucocytes and enzyme-linked immunosorbent assay (ELISA) using purified specific antigens. Of these two techniques, indirect immunofluorescence is more sensitive, while ELISA is more specific.
On indirect immunofluorescence positive for the C-ANCA pattern, staining is diffuse throughout the cytoplasm and the target antigen is PR3. This is positive in 90% of patients with granulomatosis with polyangitis (Wegener’s). The P-ANCA pattern results from staining around the nucleus, which reflects an artefact of ethanol fixation. While the target antigen in this case is MPO, antibodies to a host of azurophilic granule proteins can cause a P-ANCA pattern and these include BPI, cathepsin G and lactoferrin. Approximately 70% of patients with microscopic polyangitis are positive for P-ANCA.
The optimal approach to testing for ANCA is to screen with cheaper immunofluorescence assays and to confirm positive results with ELISAs directed against vasculitis-specific target antigens.
P-ANCA-positive sera on indirect immunofluorescence, which is classically directed against the myeloperoxidase (MPO) antigen, may be associated with concomitant positivity directed against a variety of other neutrophil antigens, such as bactericidal permeability inhibitor (BPI), cathepsin G and lactoferrin (Wong et al., 2000).
In vasculitis, the two target antigens for ANCA are proteinase 3 (PR3) and myeloperoxidase (MPO). Both PR3 and MPO are located in azurophilic granules in the cytoplasm of neutrophils and peroxidase-positive lysosomes of monocytes.
Two types of ANCA assay are indirect immunofluorescence using alcohol-fixed buffy coat leucocytes and enzyme-linked immunosorbent assay (ELISA) using purified specific antigens. Of these two techniques, indirect immunofluorescence is more sensitive, while ELISA is more specific.
On indirect immunofluorescence positive for the C-ANCA pattern, staining is diffuse throughout the cytoplasm and the target antigen is PR3. This is positive in 90% of patients with granulomatosis with polyangitis (Wegener’s). The P-ANCA pattern results from staining around the nucleus, which reflects an artefact of ethanol fixation. While the target antigen in this case is MPO, antibodies to a host of azurophilic granule proteins can cause a P-ANCA pattern and these include BPI, cathepsin G and lactoferrin. Approximately 70% of patients with microscopic polyangitis are positive for P-ANCA.
The optimal approach to testing for ANCA is to screen with cheaper immunofluorescence assays and to confirm positive results with ELISAs directed against vasculitis-specific target antigens.
Wong, R.C., Wilson, R, and Neil, J. (2000). M2-AMA do not directly produce ANCA indirect immunofluorescence patterns. J Clin Pathol 53, 643–646.
3. Answer B
The human leucocyte antigen (HLA)–DRB1 locus is associated with patients who are positive for rheumatoid factor or anti-citrullinated protein antibody (ACPA) (McInnes and Schett, 2011). Alleles that contain a common amino acid motif (QKRAA) in the HLA–DRB1 region, termed the shared epitope, confer particular susceptibility. These findings suggest that predisposing T-cell repertoire selection, antigen presentation, or alteration in peptide affinity plays a role in the mechanism of autoimmunity underlying rheumatoid arthritis. Other possible explanations for the link between rheumatoid arthritis and the shared epitope include molecular mimicry of the shared epitope by microbial proteins, T-cell senescence induced by shared epitope-containing HLA molecules, or a potential pro-inflammatory signalling function that is unrelated to the role of the shared epitope in antigen recognition. Smoking and exposure to silica increase the risk of rheumatoid arthritis among persons with susceptibility HLA–DR4 alleles. The HLA–DQB1*0602 genotype is associated with narcolepsy.
The human leucocyte antigen (HLA)–DRB1 locus is associated with patients who are positive for rheumatoid factor or anti-citrullinated protein antibody (ACPA) (McInnes and Schett, 2011). Alleles that contain a common amino acid motif (QKRAA) in the HLA–DRB1 region, termed the shared epitope, confer particular susceptibility. These findings suggest that predisposing T-cell repertoire selection, antigen presentation, or alteration in peptide affinity plays a role in the mechanism of autoimmunity underlying rheumatoid arthritis. Other possible explanations for the link between rheumatoid arthritis and the shared epitope include molecular mimicry of the shared epitope by microbial proteins, T-cell senescence induced by shared epitope-containing HLA molecules, or a potential pro-inflammatory signalling function that is unrelated to the role of the shared epitope in antigen recognition. Smoking and exposure to silica increase the risk of rheumatoid arthritis among persons with susceptibility HLA–DR4 alleles. The HLA–DQB1*0602 genotype is associated with narcolepsy.
McInnes, I.B., and Schett, G. (2011). The pathogenesis of rheumatoid arthritis. N Engl J Med 365, 2205–2219.
4. Answer C
Various innate effector cells, including macrophages, mast cells and natural killer cells, are found in the synovial membrane, while neutrophils reside mainly in synovial fluid (McInnes and Schett, 2011). Macrophages are major effectors of synovitis and act through release of cytokines [e.g. tumour necrosis factor alpha (TNF-α), interleukin-1 and others], reactive oxygen intermediates and nitrogen intermediates. Neutrophils contribute to synovitis by synthesising prostaglandins, proteases and reactive oxygen intermediates. Mast cells that produce high levels of vasoactive amines, cytokines and chemokines also play a role.
Cytokine production that arises from numerous synovial cell populations is vital to the pathogenesis of rheumatoid arthritis (RA). Cytokine patterns may shift over time with early rheumatoid arthritis having a different cytokine profile to chronic disease. TNF-α plays a fundamental role through activation of cytokine and chemokine expression, expression of endothelial cell adhesion molecules, activation of synovial fibroblasts, promotion of angiogenesis and suppression of regulatory T cells. Interleukin-1 and interleukin-6 are also abundantly expressed in rheumatoid arthritis. TNF-α promotes activation of leucocytes, endothelial cells and synovial fibroblasts. Antibody-mediated suppression of interleukins, TNF-α and, more recently, JAK kinase may be of therapeutic benefit in RA (Fox, 2012).
Various innate effector cells, including macrophages, mast cells and natural killer cells, are found in the synovial membrane, while neutrophils reside mainly in synovial fluid (McInnes and Schett, 2011). Macrophages are major effectors of synovitis and act through release of cytokines [e.g. tumour necrosis factor alpha (TNF-α), interleukin-1 and others], reactive oxygen intermediates and nitrogen intermediates. Neutrophils contribute to synovitis by synthesising prostaglandins, proteases and reactive oxygen intermediates. Mast cells that produce high levels of vasoactive amines, cytokines and chemokines also play a role.
Cytokine production that arises from numerous synovial cell populations is vital to the pathogenesis of rheumatoid arthritis (RA). Cytokine patterns may shift over time with early rheumatoid arthritis having a different cytokine profile to chronic disease. TNF-α plays a fundamental role through activation of cytokine and chemokine expression, expression of endothelial cell adhesion molecules, activation of synovial fibroblasts, promotion of angiogenesis and suppression of regulatory T cells. Interleukin-1 and interleukin-6 are also abundantly expressed in rheumatoid arthritis. TNF-α promotes activation of leucocytes, endothelial cells and synovial fibroblasts. Antibody-mediated suppression of interleukins, TNF-α and, more recently, JAK kinase may be of therapeutic benefit in RA (Fox, 2012).
Fox, D.A. (2012). Kinase inhibition – a new approach to the treatment of rheumatoid arthritis. N Engl J Med 367, 565–567.
McInnes, I.B. and Schett, G. (2011). The pathogenesis of rheumatoid arthritis. N Engl J Med 365, 2205–2219.
5. Answer B
Although not fully understood, gastrointestinal tract (GIT) involvement in scleroderma appears to be the result of autonomic nerve dysfunction of the GIT (Gabrielli et al., 2009; Gyger and Baron, 2012). In time, this autonomic nerve dysfunction leads to smooth muscle atrophy and eventually irreversible muscle fibrosis of the gut. As a consequence, hypomotility of the oesophagus, stomach, and small and large intestine are seen in patients with systemic sclerosis. Oesophageal dysmotility is associated with reflux and, eventually, strictures and even changes associated with Barrett oesophagus. Involvement of the stomach and small intestine is associated with gastroparesis and pseudo-obstruction, respectively. The presence of wide-mouth diverticula is pathognomonic of scleroderma. The lower two-thirds of the oesophagus show an absence of peristaltic waves and incompetence of the lower oesophageal sphincter. Achalasia is characterised by an increase, not a decrease, in activity of the lower oesophageal sphincter.
Although not fully understood, gastrointestinal tract (GIT) involvement in scleroderma appears to be the result of autonomic nerve dysfunction of the GIT (Gabrielli et al., 2009; Gyger and Baron, 2012). In time, this autonomic nerve dysfunction leads to smooth muscle atrophy and eventually irreversible muscle fibrosis of the gut. As a consequence, hypomotility of the oesophagus, stomach, and small and large intestine are seen in patients with systemic sclerosis. Oesophageal dysmotility is associated with reflux and, eventually, strictures and even changes associated with Barrett oesophagus. Involvement of the stomach and small intestine is associated with gastroparesis and pseudo-obstruction, respectively. The presence of wide-mouth diverticula is pathognomonic of scleroderma. The lower two-thirds of the oesophagus show an absence of peristaltic waves and incompetence of the lower oesophageal sphincter. Achalasia is characterised by an increase, not a decrease, in activity of the lower oesophageal sphincter.
Gabrielli, A., Avvedimento, E.V., and Krieg, T. (2009). Scleroderma. N Engl J Med 360, 1989–2003.
Gyger, G. and Baron, M. (2012). Gastrointestinal manifestations of scleroderma: recent progress in evaluation, pathogenesis, and management. Curr Rheumatol Rep 14, 22–29.
6. Answer C
Immune complexes are central players in the tissue injury in systemic lupus erythematosus (SLE) (Tsokos, 2011). They are formed in large amounts as anti-nuclear antibodies (ANAs) bind to the abundant nuclear material in blood and tissues, and are not cleared promptly because the Fc and complement receptors are deficient. In active SLE, complement is activated and levels of C3 and C4 depressed. In the kidney, immune complexes accumulate in the subendothelial and mesangial areas first, followed by deposition in the basement membrane and subepithelial areas. Immune complexes containing cationic anti-DNA antibodies and antibodies against the collagen-like region of C1q have an increased tendency to accumulate in the kidney. Anti-DNA and anti-nucleosome antibodies contribute to lupus nephritis, and anti-chromatin–chromatin immune complexes are present in the mesangium of patients with lupus nephritis. In addition, immune complexes may accumulate in the skin and the central nervous system. Immune complexes may bind to receptors expressed by tissue-specific cells, alter their function and cause an influx of inflammatory cells by activating the complement cascade.
Anti-Ro antibodies, which may alter the function of myocytes and cells of the conduction system, have been linked to neonatal lupus and specifically to congenital heart block. The presence of anti-Ro antibodies calls for close fetal monitoring (neonatal lupus develops in only 2% of fetuses of mothers who are positive for such antibodies) and treatment. Some anti-DNA antibodies cross-react with N-methyl-d-aspartate receptors (NMDARs); these are widely distributed across the brain, with the highest density in the hippocampus and amygdala. Anti-NMDAR antibodies in the cerebrospinal fluid and brain in patients with SLE have been linked to neurocognitive defects. Some patients with SLE have antibodies against phospholipids and β2-glycoprotein 1. The presence of such antibodies is linked to thrombotic events and fetal loss and is known as the anti-phospholipid syndrome. Anti-phospholipid antibodies interfere with the coagulation system (especially protein C) and the function of endothelial cells. These antibodies increase adhesion molecule expression on the surface of endothelial cells, induce the production of tissue factor and promote thrombosis.
Immune complexes are central players in the tissue injury in systemic lupus erythematosus (SLE) (Tsokos, 2011). They are formed in large amounts as anti-nuclear antibodies (ANAs) bind to the abundant nuclear material in blood and tissues, and are not cleared promptly because the Fc and complement receptors are deficient. In active SLE, complement is activated and levels of C3 and C4 depressed. In the kidney, immune complexes accumulate in the subendothelial and mesangial areas first, followed by deposition in the basement membrane and subepithelial areas. Immune complexes containing cationic anti-DNA antibodies and antibodies against the collagen-like region of C1q have an increased tendency to accumulate in the kidney. Anti-DNA and anti-nucleosome antibodies contribute to lupus nephritis, and anti-chromatin–chromatin immune complexes are present in the mesangium of patients with lupus nephritis. In addition, immune complexes may accumulate in the skin and the central nervous system. Immune complexes may bind to receptors expressed by tissue-specific cells, alter their function and cause an influx of inflammatory cells by activating the complement cascade.
Anti-Ro antibodies, which may alter the function of myocytes and cells of the conduction system, have been linked to neonatal lupus and specifically to congenital heart block. The presence of anti-Ro antibodies calls for close fetal monitoring (neonatal lupus develops in only 2% of fetuses of mothers who are positive for such antibodies) and treatment. Some anti-DNA antibodies cross-react with N-methyl-d-aspartate receptors (NMDARs); these are widely distributed across the brain, with the highest density in the hippocampus and amygdala. Anti-NMDAR antibodies in the cerebrospinal fluid and brain in patients with SLE have been linked to neurocognitive defects. Some patients with SLE have antibodies against phospholipids and β2-glycoprotein 1. The presence of such antibodies is linked to thrombotic events and fetal loss and is known as the anti-phospholipid syndrome. Anti-phospholipid antibodies interfere with the coagulation system (especially protein C) and the function of endothelial cells. These antibodies increase adhesion molecule expression on the surface of endothelial cells, induce the production of tissue factor and promote thrombosis.
Tsokos, G.C. (2011). Systemic lupus erythematosus. N Engl J Med 365, 2110–2121.
7. Answer H
Tocilizumab inhibits the activity of interleukin-6 (IL-6), a cytokine involved in the pathogenesis of rheumatoid arthritis (RA) and systemic juvenile idiopathic arthritis, by binding to its receptors. Elevated levels of IL-6 in the serum and synovial fluid of RA patients contribute to the chronic inflammatory process characterising RA and correlate positively with disease activity. Tocilizumab binds selectively and competitively to soluble and membrane-expressed IL-6 receptors, blocking IL-6 signal transduction. The combination therapy of tocilizumab and methotrexate was found to be more efficacious than tocilizumab monotherapy. As for its safety profile, tocilizumab was well tolerated by adult patients with early and long-standing RA.
Tocilizumab inhibits the activity of interleukin-6 (IL-6), a cytokine involved in the pathogenesis of rheumatoid arthritis (RA) and systemic juvenile idiopathic arthritis, by binding to its receptors. Elevated levels of IL-6 in the serum and synovial fluid of RA patients contribute to the chronic inflammatory process characterising RA and correlate positively with disease activity. Tocilizumab binds selectively and competitively to soluble and membrane-expressed IL-6 receptors, blocking IL-6 signal transduction. The combination therapy of tocilizumab and methotrexate was found to be more efficacious than tocilizumab monotherapy. As for its safety profile, tocilizumab was well tolerated by adult patients with early and long-standing RA.
8. Answer C
Anakinra is a recombinant form of human interleukin-1 (IL-1) receptor antagonist; it neutralises the activity of IL-1, which is involved in acute inflammatory response. Anakinra has a half-life of 4–6 h and is administered as a 100-mg subcutaneous daily injection. It has been used for treating rheumatoid arthritis and may have a role in familial Mediterranean fever.
Anakinra is a recombinant form of human interleukin-1 (IL-1) receptor antagonist; it neutralises the activity of IL-1, which is involved in acute inflammatory response. Anakinra has a half-life of 4–6 h and is administered as a 100-mg subcutaneous daily injection. It has been used for treating rheumatoid arthritis and may have a role in familial Mediterranean fever.
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