IL15 and congenital rubella syndrome: On day 0, prior to CAR-T cell infusion, several cytokines had increased plasma concentrations, including IL-15, monocyte chemoattractant protein 1 (MCP-1, CCL7), macrophage inflammatory protein (MIP) 1α and fractalkine, with more marked and statistically significant increases in patients who subsequently developed CRS (Figure 2B).