Fig. 1

Detection of circulating topoisomerase-I-specific CD4+ T cells by CD154 and CD69 expression and upregulation. After incubation (15 min) with anti-CD40 blocking antibodies, freshly isolated peripheral blood mononuclear cells (PBMCs) were stimulated for 18 h in presence of 5 % autologous serum as indicated below. Gating was set on lymphocytes, singlets, live, CD3+ and CD4+ cells. Numbers in quadrants indicate the percent (%) cells in the parent CD4+ population. a PBMCs from a healthy donor recently immunized with combined tetanus, diphtheria, and pertussis (Tdap) vaccine were stimulated with PRMT6 (negative control), SEA + SEB (positive control) and tetanus toxoid (TT). b PBMCs from a topo-I+ SSc patient were stimulated with PRMT6, PAD4 (negative controls), or topo-I. c Representative experiments on two anti-topo-I-negative and two anti-topo-I-positive SSc patients. The gating strategy for this experiment is shown in Additional file 1: Figure S1. PRMT6 protein arginine methyltransferase 6, PAD4 human peptidyl arginine deiminase type 4