Objective. To study the serologic status of 3 previously unreported monozygotic twin pairs discordant for systemic sclerosis (SSc).
Methods. Autoantibodies were measured by indirect immunofluorescence, immunodiffusion, and immunoprecipitation of 35S-labeled cell lines. Major histocompatibility complex (MHC) class 11 allele typing and DNA fingerprinting were used to confirm monozygosity.
Results. Anti-PM-Scl, anti-threonyl transfer RNA synthetase, and anti-topoisomerase I antibodies, respectively, were found in each of the twins with SSc. None of the unaffected twin siblings had an identifiable autoantibody, although serum from 1 unaffected twin precipitated several unknown proteins. The MHC class I1 genotype in each twin was the genotype expected for the autoantibody that was present.
Conclusion.
Autoantibodies of certain defined specificities are intimately linked with the development of SSc, because they segregate with SSc in individuals who start life with identical germline genes.
Systemic sclerosis (SSc) is a chronic multisystem inflammatory disorder of unknown cause that usually involves the skin (scleroderma) and microvasculature and is characterized by an accumulation of collagen in involved tissues. Immune mechanisms may