IL-13 activates tissue fibrosis [61] and genetic and observational studies link IL-13 with SSc pathogenesis [62–64].We have further demonstrated that SSc MØs express high levels of profibrotic cytokines, suggesting they play a significant role in mediating fibrosis and in maintaining an inflammatory environment in SSc (unpublished data). The gene discussed is IL13; the disease is systemic sclerosis.