This is a phase I trial to assess the safety of depleting regulatory T (Treg) cells using 1-3 doses of an interleukin-2 immunotoxin directed to the CD25 antigen (denileukin diftitox, ONTAK) in chronic lymphocytic leukemia (B-CLL) patients, followed by six subcutaneous (SC) injections of autologous leukemic cells modified ex vivo to secrete human interleukin-2 (hIL-2) and to express human CD40 ligand (hCD40L). Patients will receive a fixed dose (2 x 10e7) of IL-2 secreting B-cells together with 2 x 10e7 hCD40L expressing B-cells, representing a safe, well tolerated and immunogenic dose in our previous dose escalation study.