PF4 and systemic sclerosis: The aim of this study was to address the role of CXCL4 and the related factors (anti-CXCL4 antibodies, CXCL4–DNA or CXCL4–RNA complexes, as well as IFN-α and TNF-α) and effects in a longitudinal manner in an SSc cohort treated with iloprost.