The aim of this project is to investigate relevant pathogenetic mechanisms of Chronic lymphocytic leukemia (CLL) by dissecting the interactions occurring between the B Cell Receptor and yet unknown antigens. This will provide the basis for designing innovative and selective therapeutic strategies. CLL is the most frequent leukemia among adults in the western world, due to the accumulation of mature neoplastic B lymphocytes. CLL is an incurable disease, despite the use of intensive and costly immuno-chemotherapeutic treatments, leading to great distress for patients and their families as well as huge social costs for both public and private health care systems. A way to overcome resistance to therapy will derive from a better understanding of the molecular mechanisms of the disease that may lead to the identification of novel molecular targets for therapy. CLL is considered as a typical multifactorial disease where genetic and (micro)environmental elements concur to its pathogenesis: genetic events play a relevant role in initiating CLL but it is evident that stimuli originating from the microenvironment are responsible for maintaining and propagating the disease. Therefore, CLL may be seen as a model to elucidate the pathogenesis of cancer in general as it may reveal common oncogenic pathways acting in other neoplastic diseases.