The Scl-70 antigen is an abundant nuclear protein susceptible to proteolysis (2). It has been shown that the Scl-70 antigen can be obtained as an extractable immunoreactive fragment (70 kD) of a larger protein (100-105kD), which has been shown to be Topoisomerase I (3). Anti-Scl-70 antibodies were originally described as precipitating autoantibodies in sera of patients with a connective tissue disease. It was later realized that some patients with diffuse scleroderma characteristically have a high incidence of this autoantibody (1). The presence of autoantibodies against the Scl-70 antigen has been reported to have prognostic value in the diagnosis of diffuse scleroderma, also termed Progressive Systemic Sclerosis (1). It has also been reported that autoantibodies to Scl-70 are a specific serologic marker for Systemic Sclerosis (3), and present in high proportions of Acrosclerosis (4). Anti-Scl-70 is not usually present in other autoimmune rheumatic diseases unless some cutaneous symptoms of scleroderma are present (4).
- Maul GG, French BT, van Venrooij WJ, Jimenez SA. “Topoisomerase 1 Identified by Scleroderma 70 Antisera. Enrichment of Topoisomerase I at the Centromere in Mouse Mitotic Cells Before Anaphase.” Proc Natl Acad Sci Vol 83: 1986, pg 5145-5149.
- Douvas AS, Achten M & Tan EM. J Biol Chem 1989, pg 10514-10522.
- Shero JH, Bordwell B, Rothfiel NF, Earnshaw WC. “High Titers of Autoantibodies to Topoisomerase I (Scl-70) in Sera from Scleroderma Patients” Science Vol 231: 1986, pg 737-740.
- Jarzabek-Chorzelska M, Blaszczyk M, Jablonska S, et al. “Scl 70 antibody – a specific marker of systemic sclerosis.” British J of Dermatology 1986, pg 393-401.