To further identify the specific epitopes among these six peptides derived from DNA topoisomerase-I protein, the available PBMCs isolated from 23 SSc patients with anti-Scl-70 antibody and 9 SSc patients without anti-Scl-70 antibody were stimulated with individual peptides at the concentration of 10 μg/ml for 24 hours. The gene discussed is TOP1; the disease is systemic sclerosis.