Laminin-332 (Laminin-5) is the major motility ligand for B cell chronic lymphocytic leukemia

Cell adhesion and motility are central aspects in the pathophysiology of B cell chronic lymphocytic leukemia (B-CLL), but the role of specific extracellular matrix proteins is still to be completely unveiled. Purified peripheral blood neoplastic cells of B-CLL patients migrated poorly on laminins-111,-411,-511, but showed pronounced motility on laminin (LM)-332 in a high percentage of cases. B-CLL cell motility on LM-332 was mediated by the α3β1 integrin and was preferentially observed in cells carrying a mutated IgVH gene profile. Within normal lymph nodes, LM-332 was circumscribed around blood vessels and to areas corresponding to marginal zones, where it was deposited in a pattern reminiscent of reticular fibers. Conversely, in B-CLL involved lymph nodes, a positive LM-332 reticular mesh was diffusely evident, throughout the disrupted nodal architecture. In the present study we identified LM-332 as a crucial motility-promoting factor for B-CLL lymphocytes and as a potential constituent favoring the dissemination of B-CLL lymphocytes through vascular basement membranes and possibly lymph node compartments.