Combination of these 2 modes of stimulation resulted in ≈70% dividing CLL cells in both 2D and 3D cultures, yet 3D cultures showed a significantly increased proliferation index upon stimulation in contrast to 2D cultures (IL-2/15/21/CpG: P = 0.0297; combination: P = 0.0012) (Figure 2E). Here, IL2 is linked to B-cell chronic lymphocytic leukemia.