IL6 and congenital rubella syndrome: Cytokine release syndrome (CRS) is one of the most severe toxicities of CAR-T cell therapy due to proinflammatory cytokines including tumor necrosis factor α (TNFα), interleukin-1 (IL-1) and interleukin-6 (IL-6) produced by the activation and proliferation of CAR-T cells (84).