IL6 and congenital rubella syndrome: It is noteworthy that investigators from University of Pennsylvania (Upenn) have confirmed that endothelial cells, in particular blood-vessel endothelial cells, are the key source of IL-6 in CRS by using dual RNA ISH to examination of the IL-6 expression level of lymph node tissue from a patient who succumbed to the CRS after CTL019 infusion [15].