CD19 and leukemia: Interestingly, CD19+ leukemia cells NALM6-derived EVs carrying CD19 antigen could activate CD19 chimeric antigen receptor-T (CAR-T) cells, and transient activation dramatically promoted the release of a variety of inflammatory cytokines, including IL-2, IL-4, interferon (IFN)-γ, IL-10, IL-6, tumor necrosis factor (TNF)-α, IL2RA, IL-13, LTA and TNFSF18.