CTLA4 and B-cell chronic lymphocytic leukemia: As clinical trials with systemic administration of ipilimumab (fully human mAb directed against CTLA-4, formerly MDX-010) in CLL were recently performed [23], the results of these experiments not only broaden our knowledge about the role of the CTLA-4 molecule in the regulation of proliferation and survival of CLL cells, but also provide very important information from the clinical point of view.