Nurse-like cells (NLC) have been described as a peculiar subset of cells derived from cultures of blood mononuclear cells of CLL patients and differentiate into large, adherent cells capable of protecting leukemic B cells from apoptosis: indeed CLL cells experience a rapid decline in viability when removed from co-culture with NLC. Several studies identified factors and cellular contacts involved in increasing CLL viability. NLC attract CLL cells by secreting CXCL12 and CXCL13 and protect CLL from apoptosis through CXCL12, BAFF, APRIL, CD319 and plexin-B1.