TOP1 and systemic sclerosis: Interestingly, higher number of IFN-γ+ CD4+ T cells isolated from SSc patients who were anti-Scl-70 antibody negative was observed than that in CD4+ T cells from SSc patients with anti-Scl-70 antibody following stimulation with peptides 2, which corresponds to amino acid position 475-486 (RAVALYFIDKLA) of protein DNA topoisomerase-I (Figure 6(a)).