In a study with humanized NSG mice using a patient-derived leukaemic cell line, depletion of phagocytic cells prior to CAR T cell transplantation was enough to abrogate IL-6 production and CRS and, furthermore, single-cell analysis of leukocytes isolated during CRS identified monocyte lineage cells to be the source of IL-6 [33]. This evidence concerns the gene IL6 and congenital rubella syndrome.