In our murine model using a single intraperitoneal (i.p.)injection of 1 μg IL-15SA/IL-15RαSu-Fc, we also observed significant elevations of IFN-γ, TNF-α, and IL-10 (Figure 1A), but not IL-6 (Figure 1A; inset), which interestingly showed the greatest fold increase in the phase I clinical study of rhIL-15 [8] and was determined to be a primary cytokine mediator of toxicity in leukemia patients treated with chimeric antigen receptor effector cells [30, 31]. This evidence concerns the gene IL6 and leukemia.