CCL4 and systemic sclerosis: As TLR and IFN-γ signalling are proven to be involved in SSc pathology and are well-known activators of chemokine production by monocytes and DCs, we next determined whether the stimulation by both LPS and IFN-γ resulted in a further enhanced difference in CCL4, CXCL10, CXCL8 or IL-6 expression by monocyte subsets and DCs between SSc subsets.