Autoantibodies to the extracellular matrix microfibrillar protein, fibrillin 1, in patients with localized scleroderma

OBJECTIVE: Serum autoantibodies to fibrillin 1, the major component of microfibrils in the extracellular matrix, recently have been reported to occur in the tight skin mouse and in patients with systemic sclerosis, but not in patients with other connective tissue diseases. This study was undertaken to determine whether antifibrillin 1 antibodies could be detected in patients with localized forms of scleroderma. METHODS: Sera from 50 patients with localized scleroderma (27 with linear scleroderma and 23 with morphea) and 51 normal controls were tested for IgG and IgM antifibrillin 1 autoantibodies, using a radioimmunoassay (RIA) and a human recombinant fibrillin 1 protein (rFbn-1). RESULTS: Both in patients with linear scleroderma and in those with morphea, mean levels of IgM and IgG binding to rFbn-1 were significantly higher than in controls. Eight patients with linear scleroderma (30%) and 6 patients with morphea (26%) had IgG autoantibodies to fibrillin 1 (rFbn-1) by RIA, compared with 3 controls (6%) (P = 0.006 and P = 0.022, respectively). No correlations between antifibrillin 1 antibodies and active skin disease or antinuclear antibody positivity were found. CONCLUSION: Autoantibodies to fibrillin 1 occur in patients with both forms of localized scleroderma (linear scleroderma and morphea). The clinical and pathogenetic significance of this autoimmune response remains to be determined.