While further addressing the latter observation, we noticed that potentiation of proliferation by BPs was not effective in CpG + IL-15-stimulated cultures that lacked autologous monocyte-like Nurse-Like cells (NLCs) often recovered in CLL samples and remaining in culture attached to the bottom-well (albeit at very low density compared to the number of CLL B cells in culture). Here, IL15 is linked to B-cell chronic lymphocytic leukemia.