Antibodies to mouse laminin in patients with systemic sclerosis (scleroderma) recognize galactosyl (αl-3)-galactose epitopes

Abstract

SUMMARY: Employing radioimmunoinhibition assays with distinct oligosaccharides as inhibitors, this study demonstrates that the epitope recognized on mouse laminin by sera from patients with systemic sclerosis (scleroderma) is a terminal galactosyl (α1–3)-galactose disaccharide. The reaction with this α-digalactose was further confirmed when the sera were tested in radioimmunoassay (RIA) binding assay and in ELISA with synthetic galactose α1–3 galactosc coupled to human serum albumin. The circulating antibody appeared restricted to the IgG class and mostly to the subclass IgG3 and IgG4. Antibodies with the same specificity can be found in patients with American cutaneous leishmaniasis and Chagas disease: however, whilst in these diseases the antibody production is triggered by antigenic determinants present on the surface of the parasites, the events eliciting their appearance in systemic sclerosis are unknown.