Antinuclear antibodies in the relatives of patients with systemic sclerosis

Antinuclear antibodies were studied by indirect immunofluorescence and double immunodiffusion in 21 patients with systemic sclerosis and 35 of their relatives. When HE_p-2 cells were used as the substrate, the frequency of antinuclear antibodies in the patients' sera was 100% and that in the relatives was 26%. When rat liver sections were used, the values were 86% and 17%, respectively. Anticentromere antibody was detected in the serum from the mother of one patient whose serum had anti-Scl-70 antibody. Antibody to n-RNP was positive in the sera from the brother and daughter of another patient whose serum was positive for anti-n-RNP and anti-Scl-70 antibodies. The high frequency of antinuclear antibodies in the sera from the relatives of systemic sclerosis patients suggests that immunological abnormalities play a part in the pathogenesis of this condition.