IL4 and systemic sclerosis: While other agents (e.g., IL-4, LSP, IFNβ, IFNγ) might also induce Siglec-1 expression on monocytes/macrophages in SSc, these findings are compatible with the notion that generations of IFNα by activation of IC TLRs 3, 7, or 9 agonists might be ongoing in a subset of SSc patients (125, 167).