Perspectives in chronic lymphocytic leukemia biology and management

Novel insights in chronic lymphocytic leukemia: are we getting closer to understanding the pathogenesis of the disease?

Chronic lymphocytic leukemia (CLL) has unique epidemiologic, biologic, and clinical features. The progressively emerging picture leads us to consider that the critical genes for malignant CLL cells are those regulated by a number of microRNAs revealed by refined cytogenetic and molecular studies, and that the key molecule is the B-cell receptor (BCR). The hypothesis that CLL cells might be selected by some sort of antigenic pressure is strengthened by numerous findings indicating that a BCR-mediated stimulation plays a relevant role in the natural history of the disease and that autoantigens, as well as molecular structures instrumental in eliminating and scavenging apoptotic cells and pathogenic bacteria, may be relevant in triggering and/or facilitating the evolution of CLL. An important question is whether the tiny monoclonal B-cell populations phenotypically similar to CLL (that occur in the peripheral blood of about 3.5% of healthy individuals and are termed monoclonal B lymphocytosis) might be a critical step in the development of CLL. All relevant events of CLL occur in tissues in which a number of cellular and molecular interactions shape a microenvironment conducive to the accumulation of malignant cells and favor the organization of proliferating cells in focal aggregates of variable size that form the pseudofollicular proliferation centers. Given the impact that understanding the pathogenesis of CLL might have on the development of new treatments, the purposes of this review are to discuss whether the novel insights in CLL are leading us closer to understanding the tenet of the disease; to define the emerging new, stimulating questions; and to unfold the major challenges that still need to be addressed.

From normal to clonal B cells: Chronic lymphocytic leukemia (CLL) at the crossroad between neoplasia and autoimmunity

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy endowed with a number of features that recall autoimmune disorders, including the CD5 expression and the development of autoimmune manifestations restricted to self antigens expressed by hematopoietic cells. Several evidences strongly support the possibility that an antigenic stimulation through the B-cell receptor (BCR) is involved in the selection and possibly also the expansion of the malignant clone. Though all evidences suggest specific Ag recognition and possibly stimulation at different time-points, the nature of the Ag(s) is still unknown. It appears likely that CLL cells derive from a pool of auto/polyreactive CD5(+) B cells. Hence CLL appears to be a B-cell malignancy triggered or facilitated in its development and evolution by an auto-Ag. The crucial issues have become to what extent this deleterious binding capacity is central to the natural history of the disease and how it relates to the malignant transformation of the cell.

Transferrin receptor-1 and 2 expression in chronic lymphocytic leukemia

Transferrin receptor (TfR)-1 and 2 mRNA and CD71 (TfR1) expression was analyzed in 118 CLL patients. Ninety-five out of 109 analyzed cases expressed CD71, mostly at a high level; 60% of CD71 (+) cases were IGH-mutated. All samples were TfR1 mRNA (+); TfR2-alpha/beta mRNA was detected in, respectively, 52/102 and 100/109 cases. Competitive RT-PCR showed widely divergent levels of TfR1 mRNA in cases with high CD71 expression, alluding to post-transcriptional control of TfR1 expression in CLL. The almost uniformly high CD71 expression in CLL is in keeping with the activated status of neoplastic cells, regardless of IGH mutational load.