PF4 and systemic sclerosis: It is not excluded that, at very low concentrations of such complexes, the role of the receptor CXCR3 may become more evident; however, at the concentration of CXCL4 used in this study and previous studies and given the very high expression of CXCL4 in SSc, the role of CXCR3 seems negligible [6,7,19].