Autoantibodies to HMG-17 nucleosomal protein in patients with scleroderma

Autoantibodies to HMG-17, a non-histone nucleosomal protein, were found in systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD) and ANA positive pauciarticular juvenile rheumatoid arthritis (JRA), but not in rheumatoid arthritis (RA). Using highly purified HMG-17 derived from porcine thymus, we tested sera from 50 patients with scleroderma for antibodies to HMG-17 by enzyme-linked immunosorbent assay (ELISA). There were 16 patients with diffuse cutaneous systemic sclerosis (dSSc) and 34 with limited cutaneous systemic sclerosis (1SSc) with age at disease onset 40.25 +/- 11.68 and 39.94 +/- 15.68 years, respectively, and disease duration 6.03 +/- 4.98 and 13.34 +/- 11.80 years, respectively (P < 0.0001). Anticentromere antibodies (ACA) were found in 65% of 1SSc patients but not in dSSc (P < 0.0001) while the prevalence of antinuclear antibodies (ANA) with other than ACA patterns did not differ in the two groups. Anti-HMG-17 antibodies occurred in 20 patients (40%), five with dSSc (31%) and 15 with 1SSc (41%). Twelve of the 20 HMG-17 positive patients were also positive for ACA (60%) but this association was not significant. No association was found between anti-HMG-17 and other antibody patterns. In conclusion, anti-HMG-17 antibodies occur in one third of scleroderma patients, do not discriminate scleroderma variants and are not associated with other autoantibodies.