Impact of IL-2: six out of six donors (three HDs and three untreated CLL patients) displayed an increased proportion of CD4+ TReg and CD56+ CART cells, five out of six (three HDs and two untreated CLL patients) presented a higher absolute cell number of TEM CART cells and four out of six donors (two HDs and two untreated CLL patients) had an increased proportion of CD4−CD8− cells within their CART product compared to generation in IL-7/IL-15. Here, IL2 is linked to B-cell chronic lymphocytic leukemia.