CX3CL1 and B-cell chronic lymphocytic leukemia: Furthermore, NLCs are attracted by CLL cells that secrete CX3CL1/Fractalkine and, once in contact, adhesion of NLCs and CLL cells may be strengthened by homotypic (CLL to CLL or NLC to NLC) or heterotypic (CLL to NLC) interactions driven by surface CX3CL1 and CX3CR1 [17].