To determine the clinical and immunogenetic features of systemic sclerosis (SSc) patients with anti-Th/To autoantibodies. Methods. HLA class I1 alleles were determined by DNA oligotyping in a large group of SSc patients with anticentromere antibodies (ACA), anti-topoisomerase I (anti-top0 I), and anti-Th/To autoantibodies. Results. Clinical features of the 28 anti-Th/Topositive SSc patients were similar to those observed in the 56 ACA-positive SSc patients, except for a decreased frequency of gastrointestinal involvement in anti-Th/ To-positive patients. Immunogenetic analysis revealed a significant increase in the frequency of HLA-DRl1 in the anti-Th/To-positive and the anti-top0 I-positive patients. The anti-Th/To-positive patients also had a significant reduction in the frequency of HLA-DR7, similar to that seen in ACA-positive SSc patients. Conclusion. Despite clinical and immunogenetic similarities with both the ACA-and anti-top0 I-positive patients, anti-Th/To-positive SSc patients present a characteristic pattern of clinical and immunogenetic features that may have implications regarding etiology, pathogenesis, and treatment.
Systemic sclerosis (SSc) is a multisystem connective tissue disease of unknown etiology that is thought to have an autoimmune origin. This hypothesis is based on the fact that most SSc patients have circulating antibodies to self nuclear proteins and that infiltrates of T lymphocytes are observed in early cutaneous lesions (1).