CRS is believed to be a result of the sustained activation of a variety of cell types such as monocytes and macrophages, T cells and B cells, and is characterized by an increase in levels of TNFα and IFNγ within 1 to 2 h of stimulus exposure, followed by increases in interleukin (IL)-6 and IL-10 and, in some cases, IL-2 and IL-8. This evidence concerns the gene IL6 and congenital rubella syndrome.