The never ending story of the origin of Chronic Lymphocytic leukemia.
Speaker: Paolo Ghia
Università Vita-Salute San Raffaele. Milan (Italia)
Host: Alberto Orfao/Julia Almeida
Salón de Actos del CICThe never ending story of the origin of Chronic Lymphocytic leukemia.
The cell origin of Chronic Lymphocytic Leukemia (CLL) has been a topic of intensive research since long, though remaining quite elusive. A great advancement has been achieved with the detection of Monoclonal B lymphocytes circulating in the peripheral blood of otherwise healthy individuals. Their presence at a concentration of <5x109/L, in the absence of clinical signs of an active lymphoproliferative disorders (B symptoms, lymphoadenopathies, enlarged spleen or liver), is now defined as Monoclonal B cell Lymphocytosis (MBL), a novel entity whose frequency is increasing with age and in most cases shows a phenotype identical to CLL, with low levels of CD20 and high expression of CD5. In the general adult population, it can be detected in 5-10% of individuals depending on the sensitivity of the assay used. They can be present at dramatically different cell concentration ranging from few cells (1-50cells/L) to few thousands (1.5-4.9x106/L). While the latter cases show a low but sizeable (1-2% per year) risk of evolution into a clinically relevant CLL, the former appear to be stable and seem more likely to be related to immunoscenence processes. Biological and immunological features corroborate the notion of a clear distinction between these two entities now named as Low-count and High-count MBL, respectively. These findings suggest a different clinical management that requires a follow-up only in HC-MBL similar to Stage 0 CLL patients who carry a higher but similar (5%/year) risk of clinical progression. The study of the biological, genetic and functional features of these cells and the relationship with CLL will help to better distinguish those cases who are at higher risk of leukemic evolution, in order to exclude from clinical follow-ups those who will likely never develop clinical consequences for the presence of monoclonal B Lymphocytes.