IL1B and congenital rubella syndrome: IL-6 is primarily synthesized by activated T cells, with additional contributions from endothelial cells in the vasculature and the monocyte/macrophage lineage in the context of CRS.471–474 Elevated IL-6 levels have been associated with vascular permeability, complement activation, DIC, and myocardial dysfunction.216 Recent studies have highlighted the role of inducible nitric oxide synthase (iNOS) as a proinflammatory cytokine expressed by M1 macrophages in the pathogenesis of CRS.470 IL-1β has been shown to stimulate the expression and synthesis of iNOS.