Levels (mean, range) of antibodies to anti-Ap1-17 (panel A), -Ap17-30 (panel B) and anti-FOXE3p53-62 (panel C) in patients with systemic sclerosis (anticentromere antibody-positive and -negative) and systemic lupus erythematosus, and in healthy blood donors. Ab levels were measured by enzyme-linked immunosorbent assay (ELISA), using appropriate standard curves. The proportion of the difference of the levels between groups was evaluated by the Mann-Whitney U-test. P <0.05 was considered significant. Ab, autoantibodies; ACA+, anticentromere antibody-positive; ACA-, anticentromere antibody-negative; SLE, systemic lupus erythematosus; HBD, healthy blood donors.