Clinical significance of anti‐topoisomerase I antibody levels determined by ELISA in systemic sclerosis

OBJECTIVE: To determine the clinical associations of the levels of anti-topoisomerase I (topo I) antibody in patients with systemic sclerosis (SSc). METHODS: Anti-topo I antibody levels were determined by enzyme-linked immunosorbent assay. In a longitudinal study, 125 sera from 21 patients were analysed during a follow-up period of 0.2-4.7 yr. RESULTS: Anti-topo I antibody levels were correlated positively with skin thickness score and renal vascular resistance, and inversely with percentage vital capacity. In the longitudinal study, five patients with a low anti-topo I antibody level at their first visit exhibited a stable antibody level or a small decrease in the level during the follow-up period, and their skin sclerosis was stable. Of 16 patients with a high anti-topo I antibody level at their first visit, seven showed a stable level, four had an increasing level and five had a decreasing level. The decreasing levels were accompanied mainly by atrophic skin change during the follow-up period, whereas the increasing levels were associated with new onset or worsening of organ involvement. CONCLUSIONS: These results suggest the potential clinical significance of anti-topo I antibody levels in evaluating disease severity and the prognosis in SSc.