Progressive Systemic Sclerosis (PSS), is a chronic systemic rheumatic disease that can effect many organ systems including the skin, the GI tract, the heart, lungs and kidneys. It occurs more commonly in females and its onset most frequently in the ages from 20 to 50 years. Sera from patients with PSS contain several autoantibodies to different nuclear antigens including Scl-70, Sm and centromere antigens. Antibody to Scl-70 (topoisomerase I) is present in around 20% of patients with scleroderma, particularly those patients with a more progressive form of the disease. Scl-70 is difficult to detect by immunofluorescent studies where it gives fine speckles within the nucleus. Scl-70 antigen is present in the ENAscreen.Samples positive for the ENAscreen but negative for Ro, La, RNP, Sm or the centromere antigen will automatically be tested for Scl-70. However, since many Scl-70 sera are also positive for other ENAs (Ro52or RNP) it is best to specifically request Scl70 or give scleroderma as clinical details where appropriate.
Diagnosis of Scleroderma, systemic sclerosis.
Present in 15 – 20% cases of scleroderma. Marker of systemic disease “Scleroderma” covers a group of heterogeneous but related diseases all displaying a greater or lesser amount of dermal thickening. Other symptoms include pulmonary changes (fibrosis), sclerodactyly, Raynaud’s phenomenon, subcutaneous calcifications, oesophageal dysmotility and neurological symptoms such as brachial plexopathy, paraesthesia and optic neuritis.Scl-70 is associated with around 15-30% of cases of diffuse cutaneous systemic scleroderma (dcSSc). Anti-Scl-70 antibodies occur less commonly in Caucasians than some other racial groups. The levels do not correlate with disease activity.
Fluorescence enzyme linked immunoassay (Phadia Immunocap 250): Human recombinant Scl-70 protein ; IgG antibodies.
Test is only carried out when ENA screen is positive.
Results reported as negative, equivocal or positive.
5 – 7 days
Immunology The James Cook University Hospital