Immunology

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Notes

Useful for:

• Investigation of patients with Connective Tissue Disease.

Clinical Information:

• The Connective Tissue Disease Screen includes:
• dsDNA: IgG antibodies directed against Double Stranded DNA (dsDNA) are present in up to 70% of patients with Systemic Lupus Erythematosis (SLE) and form part of the diagnostic criteria.
• SS-A/Ro antibodies: These can be found in approximately 90% of patients with Sjogrens Syndrome. Additionally 40-60% of patients with Lupus Erythematosis (LE) also produce these antibodies. In the Lupus Erythematosis (LE) group of patients the antibodies are often associated with childhood and neonatal Lupus Erythematosis (LE) and with congenital heartblock in infants born to mothers who have Lupus Erythematosis (LE).
• SS-B/La antibodies: These can be found in approximately 60% of patients with Sjogrens Syndrome. Additionally 15% of patients with Lupus Erythematosis (LE) also produce these antibodies. Usually SSA-B/La antibodies co-occur with SS-A/Ro antibodies.
• Sm (Smith) antibodies: These are found in approximately 30% of patients with Lupus Erythematosis (LE) and are specific for the disease. Usually Sm antibodies co-occur with RNP antibodies in patients with Lupus Erythematosis (LE).
• U1-RNP antibodies: These are found in approximately 50% of patients with Lupus Erythematosis (LE). High levels of these antibodies in the absence of Sm and double-stranded DNA (dsDNA) antibodies are indicative of Mixed Connective Tissue Disease (MCTD).
• Jo-1 antibodies: These can be found in approximately 50% of patients with polymositis who also display interstitial lung disease.
• Scl-70 antibodies: These are found in approximately 60% of patients with Scleroderma and are specific for the disease. Patients often have extensive cutaneous involvement and interstitial pulmonery fibrosis.
• CENP (centromere) antibodies: found in 70-90% of patients with CREST Syndrome, a limited form of scleroderma. They may also occur in Raynaud's phenomenon and primary biliary cirrhosis (about 10-20%).
• Fibrillarin antibodies: Occur in less than 15% of patients with scleroderma and seem to be associated with internal organ involvement including pulmonary hypertension, myositis, and renal disease.
• RNA polymerase III antibodies: Highly specific for scleroderma and are more frequent in patients with diffuse cutaneous scleroderma (35-45%) than in those with limited cutaneous scleroderma.
• Antibodies against Ribosomal P Proteins (PO, P1 and P2): These autoantibodies are found in approximatley 23% of patients with active Systemic Lupus Erythematosis (SLE) and are associated with neuropsychiatric, renal and hepatic involvement.
• Polymyositis-Scleroderma (PM-Scl) antibodies: Approximatley 24% of patients with Myositis-Scleroderma Overlap Syndrome and only 2% of the patient population with scleroderma have PM-Scl Antibodies. They correlate with a benign course of disease and respond well to steroid therapy.
• Proliferating Cell Nuclear Antigen (PCNA) Antibodies: occur in 2 to 10% of Systemic Lupus Erythematosis (SLE) patients and are not very specific. They are also found in 12.3% of Hepatitis B and 18.7% of Hepatitis C patients, respectively.
• Mi-2 Nuclear Antigen Antibodies: are highly specific for dermatomyositis and polymyositis. Approximately 31% of patients with dermatomyositis have Mi-2 Nuclear Antigen Antibodies.

Please Note:

• Any paediatric sample positive for Centromere antibodies will be confirmed by Indirect Immunofluorescence using Hep2 Slides (ANA). 
• Only samples that have an equivocal or positive Connective Tissue Disease screen will have further testing to determine the individual antigens present. Please see the Connective Tissue Disease Testing Algorithm in the 'Related Links' section.
• Where External Institiutions cannot guarantee immediate delivery, samples must be centrifuged, separated and stored at 4^oC. Samples can then be transported, as soon as possible, to St. James's Hospital for processing.

Related links

https://www.stjames.ie/intranet/oncampus/departments/immunology/formsbooklets/CTD,Testing,Algorithm.pdf 

Reference range

The CTD screen is reported as a Ratio:

<0.7 = Negative

0.7-1.0 = Equivocal

>1.0 = Positive

Individual antigens:

SSA/Ro, SSB/La, Sm, Jo-1, Centromere and Scl70:

<7.0 U/ml = Negative

7.0-10 U/ml = Equivocal

>10 U/ml = Positive

u1-RNP:

<5.0 U/ml = Negative

5.0-10 U/ml = Equivocal

>10 U/ml = Positive

dsDNA:

<10.0 U/ml = Negative

10-15 U/ml = Equivocal

>15 U/ml = Positive

Last updated

Mon, 08 Jan 2024 08:06:32 GMT