IgG reactivity with a 100-kDa tissue and endothelial cell antigen identified as topoisomerase 1 distinguishes between limited and diffuse systemic sclerosis patients

We have analyzed antibody (Ab) reactivities of patients with limited systemic sclerosis (SSc) and anti-centromere Ab, patients with diffuse SSc and anti-topoisomerase 1 (anti-topo 1) Ab, patients with diffuse SSc without anti-topo 1 or anti-centromere Ab and age- and gender-matched healthy controls with normal human tissue and endothelial cell (EC) antigens. activities with tissue antigens differed significantly between patients with anti-topo 1 Ab and patients with anti-centromere Ab. One 100-kDa band identified as topoisomerase 1 in macrovascular and microvascular EC extracts was recognized by IgG from patients with anti-topo 1 Ab and 50% of patients without specific Ab. IgG from patients with limited SSc and anti-centromere Ab, but not those of other patients or controls specifically recognized a 80-kDa band only in microvascular EC. Our results indicate that Ab from patients with limited or diffuse SSc with or without anti-topo 1 Ab exhibit specific and mutually exclusive reactivity patterns.