To investigate if neutrophil activation occurs in SSc, we analyzed levels of calprotectin (S100A8/A9) as well as NETs (MPO-DNA complexes) in plasma samples from a large cohort of patients with SSc (n=80, Cohort I, Table 1) as well as in a smaller validation cohort (n=20, Cohort II, Table 1) and compared them with levels found in healthy controls (n=40, Cohort I and n= 24, Cohort II). This evidence concerns the gene MPO and systemic sclerosis.