OBJECTIVE: To develop an overview focusing on the utility of anti-Scl-70 autoantibody determinations in the rheumatic diseases. METHODS: Articles from electronic literature searches were retrieved, critiqued and data were extracted and pooled on anti-Scl-70 (topoisomerase I) in relation to history, optimal tests used for its detection, sensitivity, specificity, positive and negative likelihood ratios, indications, interpretation and pitfalls. RESULTS: Anti-Scl 70 antibodies are very useful in distinguishing systemic sclerosis (SSc) patients from healthy controls, from patients with other connective tissue diseases, and from unaffected family members. Among patients with SSc, anti-Scl-70 positivity is useful in predicting those at higher risk for diffuse cutaneous involvement and interstitial fibrosis/restrictive lung disease, though the latter has not been universally observed. Of the four different techniques notably immunodiffusion, immunoblotting, immunoprecipitation and enzyme-linked immunosorbent assay (ELISA) used to assay anti-Scl-70, immunodiffusion has been the most extensively validated. ELISAs are somewhat less specific than other techniques, especially in distinguishing SSc patients from those with other rheumatic diseases, though newer generation ELISAs have been developed to overcome the problem of low specificity inherent with the traditional techniques. As of yet, the need for serial testing of anti-Scl-70 has not been established. CONCLUSIONS: Evidence-based guidelines suggest that anti-Scl-70 antibodies are very useful in the diagnosis and clinical management of SSc patients and also to establish prognosis in these patients, particularly those with diffuse skin involvement.
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