IL6 and congenital rubella syndrome: First, whether IL-6 blockade impairs the in vivo proliferation of CAR T cells is still debated, because IL-6 has been clearly proven to promote the proliferation of T cells.96–98 In addition, it has been reported that the serum IL-6 levels may rapidly rise after tocilizumab administration.99 According to our clinical observations, it is noteworthy that L-CRS can be aggravated by the use of tocilizumab.