defect in apoptosis, and that malignant lymphocytes accumulate due to diminished cell death [1, 2]. Consistent with this theory, CLL cells are relatively inert, do not proliferate, and accumulate until levels not supportable by a patient. However, this original view has been challenged in the last ten years. Several reports showed that high lymphocyte count in CLL patients is caused not only by the prolonged survival, but also by proliferating cells from the bone morrow, spleen or lymph nodes [3–5]. Immune incompetence is another important feature of CLL. Most patients develop severe hypogammaglobulinemia and impaired immune response to antigens [6].
